8th Grade ELA Quiz: Establish Maintain Formal Explanatory Style

What this quiz covers

This quiz focuses on Establish Maintain Formal Explanatory Style, giving you a quick way to practice the rules, question types, and explanations that matter most for 8th Grade ELA.

How to use this quiz

Try each quiz question before looking at the correct answer. Use the explanations to review missed ideas, then come back to similar questions until the pattern feels familiar.

Question 1

1. The process by which a bill becomes a law starts once it gets introduced and then goes through a bunch of committees, which is basically a pretty long and complicated journey from start to finish.
2. This explanation will describe how a bill becomes a law after people talk it over in committees and then decide together whether the idea is good enough to keep moving it forward.
3. The process by which a bill becomes law begins with its introduction in a legislative chamber and continues through committee review and additional votes before final approval. (correct answer)
4. The path a bill follows to become a law starts when a lawmaker suggests an idea and then guides it along until everyone in government finally agrees to sign off on the whole thing.

Explanation: The best revision keeps the focus on the topic rather than the writer and reports the process with precise governmental terms: a bill "begins with its introduction in a legislative chamber and continues through committee review and additional votes before final approval." This reads as objective, informative writing built from exact process vocabulary. The revision about a bill going "through a bunch of committees, which is basically a pretty long and complicated journey" stays in third person but relies on casual, vague wording instead of precise legislative terms, so its tone is not formal. The revision that says people "talk it over in committees and then decide together whether the idea is good enough" describes people and their opinions rather than the objective steps of the process, and its loose phrasing keeps the tone conversational. The revision in which a lawmaker "suggests an idea" and "everyone in government finally agrees to sign off on the whole thing" reads smoothly but uses everyday expressions instead of accurate process terminology, so it also stays informal. Only one choice sustains an objective tone and exact vocabulary throughout, so it is the best answer.

Question 2

1. Hurricanes are enormous storms that terrify coastal communities and leave people feeling absolutely powerless when they finally slam into land.
2. A hurricane forms over warm ocean water when moist air rises, condenses, and releases heat energy that fuels stronger winds. (correct answer)
3. Most scientists believe hurricanes develop because the ocean surface heats up, and that extra warmth is what makes each storm grow more powerful.
4. A hurricane happens when a swirling storm keeps getting bigger and bigger until it simply cannot manage to stop spinning around.

Explanation: The best choice explains how a hurricane forms using precise, third-person, objective language: it names specific processes—warm ocean water, moist air rising, condensing, and releasing heat energy that fuels stronger winds. It presents the information neutrally, without opinion or emotion, which is exactly what a formal explanatory report requires. The sentence calling hurricanes 'enormous storms that terrify' relies on emotional, dramatic wording ('terrify,' 'absolutely powerless') that belongs in persuasive or narrative writing, not objective explanation. The sentence beginning 'Most scientists believe' hides behind vague attribution and imprecise phrasing ('heats up,' 'grow more powerful') instead of stating the process directly and precisely. The sentence about a storm that 'keeps getting bigger and bigger' uses casual, repetitive language ('bigger and bigger,' 'simply cannot manage') that sounds conversational rather than formal, and it never explains the actual cause. Only the keyed sentence combines objectivity, precise vocabulary, and a clear explanation of the process, so it is the single best fit for a formal explanatory style.

Question 3

1. A bill is introduced in either the House of Representatives or the Senate and is then assigned to a committee for careful review and consideration.
2. If the bill passes both chambers, it is sent to the President, who then may choose to sign it into law or to veto it entirely.
3. This important process includes formal debate, careful revision, and recorded voting in order to determine whether the proposal finally becomes law.
4. At that point, the lawmakers are basically trying to figure out whether the idea is any good, and things can honestly get pretty intense. (correct answer)

Explanation: The best answer is the sentence that abandons a formal explanatory style. Words like "basically," "any good," and "honestly" are casual, conversational fillers, and "can get pretty intense" adds a personal, emotional judgment instead of neutral information. That mix of slang and opinion is out of place in an academic explanation, so it is the least appropriate choice. The sentence about a bill being introduced in the House or Senate and assigned to a committee stays formal: it uses precise governmental terms and an objective, third-person tone, so it does NOT break the style. The sentence describing the bill passing both chambers and going to the President keeps the same formal register, using accurate terms like "chambers" and "veto" and presenting options neutrally. The sentence about debate, revision, and voting also maintains formality through precise process vocabulary and the objective phrase "in order to determine." Because each of these three reads like textbook explanation, only the slang-filled, opinion-driven sentence fits the stem's request for the least appropriate choice.

Question 4

1. Bacteria reproduce through binary fission, a fairly straightforward process in which the cell splits in half, so populations end up growing without much difficulty at all.
2. Bacteria reproduce through binary fission, in which a cell copies its DNA and divides, which is basically just how they end up multiplying so quickly.
3. Bacteria reproduce through binary fission, a process in which one cell replicates its DNA and divides into two genetically identical cells. (correct answer)
4. Binary fission is the simple process through which one cell copies its own DNA and then splits, producing two new cells that basically look the same.

Explanation: The original paragraph opens formally but then drops into casual, evaluative language ("like," "basically," "not that complicated"). A consistent formal explanatory style stays precise, objective, and free of conversational asides. The revision describing one cell that replicates its DNA and divides into two genetically identical cells does exactly this: it reports the process without judging it or adding filler. The revision calling the process "fairly straightforward" and saying populations grow "without much difficulty" inserts an informal opinion that breaks the objective tone. The revision ending with "basically just how they end up multiplying so quickly" keeps the same casual filler ("basically just") that made the original inconsistent. The revision that labels the process "simple" and says the two cells "basically look the same" trades exact wording for loose, everyday phrasing. Only the revision that stays neutral and precise throughout maintains one steady formal register from beginning to end, so it is the single best answer.

Question 5

1. The paragraph relies on very short, choppy sentences, which prevents the writer from linking ideas with the transitions expected in formal explanation.
2. The paragraph includes subjective, conversational commentary (for example, "honestly" and "it feels like"), which shifts from objective explanation to personal opinion. (correct answer)
3. The paragraph repeats the word "laws" in three consecutive sentences, and this repetition makes the tone too casual for a formal explanatory paragraph.
4. The paragraph presents the three branches in a plain factual list, and that neutral, information-first approach lacks the persuasive voice that formal writing requires.

Explanation: The paragraph starts strong: the first three sentences keep a third-person, objective focus and use precise government vocabulary like "legislative," "executive," and "judicial." The final sentence breaks that formal explanatory style. Words like "honestly," "kind of confusing," "it feels like," and "anyway" add personal opinion and a casual, conversational voice, shifting the writing from explaining the topic to sharing the writer's feelings about it. That is why the choice pointing to subjective, conversational commentary is correct. The other options misjudge what formal style requires. Short sentences are not the problem; a formal explanation can use brief, direct sentences, and these clearly connect one idea to the next. Repeating "laws" is a normal way to stay precise about the subject and does not make the tone casual. And presenting the branches as a plain factual list is exactly what formal explanatory writing should do—explanation aims to inform objectively, not to persuade, so a neutral, information-first approach is a strength, not a weakness.

Question 6

1. No; although it stays in third person, its technical vocabulary is too specialized and should be replaced with first-person statements sharing the writer's personal connection to energy issues.
2. No; although its facts are accurate, the neutral tone is too detached and should add emotional, vivid language that persuades readers to care deeply about the topic.
3. Yes; it keeps a third-person, objective tone and relies on precise domain vocabulary to explain the process clearly for its readers. (correct answer)
4. Yes; although it explains a process step by step, it works mainly because its relaxed word choices and everyday phrasing make the science feel approachable to readers.

Explanation: The best answer says the style is appropriate because the excerpt keeps a third-person, objective tone and uses precise domain vocabulary—"photovoltaic cells," "electric current," "greenhouse gas emissions"—to explain the process accurately. That combination is exactly what formal explanatory writing requires. The choice that wants the technical vocabulary swapped for first-person personal statements is wrong: formal explanations rely on that precise vocabulary and avoid the writer's personal intrusion, so removing it would weaken the writing. The choice demanding emotional, persuasive language is wrong because explanatory writing informs readers neutrally rather than trying to persuade them to feel a certain way; the detached tone is a strength here, not a flaw. The choice claiming the passage succeeds because of relaxed word choices and everyday phrasing misreads the text—the excerpt actually uses formal, technical language with no casual wording, so this reasoning credits a quality the passage does not have. Only one choice correctly matches the excerpt's real features to the demands of formal explanatory style.

Question 7

1. Vaccines train the immune system to recognize specific pathogens by introducing a harmless form or component, which helps the body respond more effectively during future exposure. (correct answer)
2. Vaccines expose the body to a safe version of a germ so that the immune system can learn to recognize it, and honestly they help out a whole lot with staying healthy.
3. Vaccines are not some kind of magic trick, yet they remain incredibly great tools because they help people avoid getting sick from dangerous diseases.
4. In this paragraph, I want to explain that vaccines work because the immune system studies a germ and then remembers exactly how to fight it later.

Explanation: The best revision keeps the focus on the topic rather than the writer, uses precise scientific vocabulary such as "pathogens" and "future exposure," and describes the process in a neutral, objective tone: "Vaccines train the immune system to recognize specific pathogens by introducing a harmless form or component." This is the formal explanatory style a science report calls for. The version ending with "they help out a whole lot with staying healthy" starts formally but slips into a casual, conversational tone with the word "honestly" and vague intensifiers, so the register is inconsistent. The version that calls vaccines "not some kind of magic trick" and "incredibly great tools" relies on emotional, opinion-based language instead of objective explanation. The version beginning "In this paragraph, I want to explain" uses first person and turns the focus onto the writer rather than the topic, which is not appropriate for formal explanatory writing. Only the first option maintains an objective, third-person, precise style throughout.

Question 8

1. The draft is fully appropriate because the personal example at the end adds vivid detail that always strengthens the objective explanatory tone.
2. The draft is mostly formal at first, but the personal anecdote and emotional word choice reduce the objective explanatory tone. (correct answer)
3. The draft is inappropriate because the technical terms like "sediment" and "weathered rock" sound too formal for a student explanatory piece.
4. The draft is inappropriate because the opening sentences avoid first person, and explanatory writing needs a personal voice to feel real.

Explanation: The best answer says the draft starts formal but loses its objective tone at the end. The first two sentences explain erosion in third person with precise terms like "weathered rock," "sediment," and "transport." The last sentence breaks that style: "I have seen this happen at my cousin's house" shifts to a personal story, and "it is crazy how fast" adds casual, emotional language. That mix is exactly why the draft is only partly appropriate. The choice claiming the personal example always strengthens the writing is wrong—personal anecdotes pull the focus away from objectively explaining the process, so they weaken formal explanatory tone here. The choice calling terms like "sediment" too formal is wrong—precise, domain-specific vocabulary is exactly what explanatory writing should use, so those words are a strength, not a flaw. The choice saying explanatory writing needs first person and personal voice is wrong—formal explanations usually stay in third person and objective, so the opening sentences are correct rather than a problem.

Question 9

1. Wind turbines generate power when wind spins the blades, but they do not really work without steady wind, so they are kind of unreliable overall.
2. Wind turbines generate electricity when wind turns the blades connected to a generator; however, output decreases when wind speeds are low. (correct answer)
3. Wind turbines are impressive machines that generate electricity, although they unfortunately cannot always produce power when the weather does not cooperate.
4. I think wind turbines usually generate electricity from wind, but in my opinion they probably do not always work depending on the weather conditions.

Explanation: The best revision keeps the focus on the technology, uses precise domain vocabulary, and states the limitation as an objective fact: it explains that the blades are "connected to a generator" and that "output decreases when wind speeds are low." This is more accurate than saying turbines simply stop working, and it stays neutral and third-person throughout. The option using "generate power" and "kind of unreliable" loses precision by hedging casually and labeling the turbines with a vague, subjective judgment instead of describing what actually happens. The option calling turbines "impressive machines" that "unfortunately cannot" work adds emotional, evaluative language ("impressive," "unfortunately") that does not belong in objective explanatory writing. The option beginning "I think" and adding "in my opinion" and "probably" shifts into first-person opinion and uncertainty, which is inappropriate for presenting factual information. Only the keyed revision maintains a formal, objective tone while making the description more exact, so it is the single best answer.

Question 10

1. In a chemical reaction, atoms rearrange to form new substances, and you can tell it is happening because the changes you see are usually pretty obvious to anyone watching.
2. In a chemical reaction, atoms rearrange to form new substances, and observers can often identify evidence such as color change, temperature change, or gas production. (correct answer)
3. In a chemical reaction, atoms rearrange to form new substances, and you can tell it is happening because it is like the substances are turning into something totally different.
4. In a chemical reaction, atoms rearrange to form new substances, and you can tell it's happening because there are bubbles and other signs appearing in the mixture.

Explanation: The teacher asked for two things: no contractions and an objective tone. An objective, formal explanation keeps the focus on the topic instead of speaking directly to the reader. The best revision replaces "you can tell" with "observers can often identify," which shifts to a neutral third-person viewpoint, and it names precise evidence: color change, temperature change, or gas production. That combination meets both requirements. The option about changes being "pretty obvious to anyone watching" stays in second person ("you can tell") and uses vague, subjective wording instead of objective language. The option comparing the reaction to substances "turning into something totally different" relies on a loose, informal comparison rather than precise explanatory detail, and it also keeps the second-person "you." The option ending with "there are bubbles and other signs" breaks the no-contractions rule ("it's") and stays casual and imprecise. Only the revision using "observers can often identify" keeps a consistent, objective, contraction-free style throughout.

Question 11

1. The main problem is the specialized vocabulary, such as "tectonic plates" and "seismographs," because these technical terms are too advanced for a general reader and make the paragraph sound stiff instead of approachable and clear.
2. The main problem is the writer's personal framing, casual words such as "kind of," "pretty," "totally," and "stuff," and emotional wording that pulls attention away from an objective explanation of the topic. (correct answer)
3. The main problem is the sentence variety, because the draft mixes short and long sentences unevenly, and a formal explanation should keep every sentence about the same length to maintain a steady, professional rhythm throughout.
4. The main problem is the organization, because the draft explains the causes and effects of earthquakes rather than narrating a single earthquake event as a story with a clear beginning, middle, and end.

Explanation: The best answer points to the writer's personal framing ("I am going to explain"), the casual words ("kind of," "pretty," "totally," "stuff"), and the emotional wording ("pretty scary," "people freak out"). These features make the writing sound conversational and center the writer's feelings instead of the topic, which is what breaks a formal, objective style. The choice about specialized vocabulary is wrong because "tectonic plates" and "seismographs" are the exact, correct terms for this subject; precise technical words belong in explanatory writing and do not make it informal. The choice about sentence variety is wrong because mixing short and long sentences is normal, effective writing; formal style does not require every sentence to be the same length, so this is not the flaw. The choice about organization is wrong because explaining causes and effects is exactly what an informational paragraph should do; turning the topic into a story would not fix the informal tone, so organization is not the issue.

Question 12

1. The excerpt relies on domain-specific terms such as "fault" and "seismic waves," which are too advanced for the audience and should be replaced with simpler everyday words.
2. The excerpt includes subjective and conversational language, such as "honestly," "kind of," "totally," and "I think," which shifts away from an objective explanatory tone. (correct answer)
3. The excerpt mixes verb tenses between present and past, such as "occur" and "slip," which breaks the consistency that explanatory writing requires throughout.
4. The excerpt combines several ideas into one long compound sentence, which makes the writing too complex to count as clear explanatory writing.

Explanation: The excerpt starts strong: "Earthquakes occur when stress builds along a fault... releasing energy as seismic waves" keeps a third-person, objective tone with precise science terms. Then it breaks down. Words like "honestly," "kind of," "totally," and "I think" turn the passage into casual, personal reaction instead of neutral information. That is the choice about subjective and conversational language, and it correctly names why the formal style collapses. The choice about domain-specific terms is wrong because "fault" and "seismic waves" are exactly the precise vocabulary formal explanatory writing wants; replacing them would weaken the style, not strengthen it. The choice about mixed verb tenses misreads the passage: "occur" and "slip" are both present tense, so tense is consistent and is not the problem. The choice about one long compound sentence is wrong because explanatory writing can and does use complex sentences; sentence length is not what damages the tone here. The real weakness is register, not structure or vocabulary.

Question 13

1. The Underground Railroad was a network of secret routes and safe houses that assisted enslaved people in escaping to free states and Canada. Participants faced serious risks and relied on careful planning, limited resources, and cooperation. (correct answer)
2. The Underground Railroad was a bunch of secret routes and safe places that were really brave to use. People did not have a lot of stuff, but it is crazy how they kept going and pulled it off anyway.
3. I am going to tell you about the Underground Railroad, which was a bunch of routes that helped people escape to free states and Canada even when they did not have a lot of stuff to work with.
4. The Underground Railroad was, like, a bunch of secret routes and safe places, and it is honestly wild how those super brave people managed to pull the whole thing off with barely any resources.

Explanation: The best revision keeps a formal explanatory style from start to finish. It uses precise, academic vocabulary ("network," "safe houses," "assisted," "participants," "limited resources"), stays in an objective third-person point of view, and reports the facts in complete sentences without opinions or slang. It also keeps every main idea: what the Underground Railroad was, the risks people faced, and their lack of resources. The other choices keep casual or personal language that does not fit a formal explanation. One recycles the draft's informal words—"a bunch," "really brave," "a lot of stuff," "crazy," and "pulled it off"—so it reads like conversation, not explanation. Another opens with "I am going to tell you about," which is first person and announces the topic instead of objectively presenting it, and it still uses "a bunch" and "a lot of stuff." The last one is the most conversational of all, using fillers and slang like "like," "honestly wild," "super brave," and "pull the whole thing off." Because a formal explanatory style requires objective tone, precise vocabulary, and no slang or personal commentary, only the first revision fully qualifies.

Question 14

1. "Earthquakes occur when stress builds up along faults in Earth’s crust until the rocks slip and release energy," because opening with a definition of a process is too basic for a serious report.
2. "This energy travels as seismic waves that can cause the ground to shake," because describing what waves do makes the explanation sound more like a story than a report.
3. "But honestly, it is kind of like the Earth just snapping because it cannot take it anymore, and that is pretty scary," because it turns to casual asides, emotion, and imprecise wording. (correct answer)
4. The use of the term "seismic waves," because such technical vocabulary sounds too advanced and could confuse readers of a science report.

Explanation: A formal explanatory report keeps an objective, third-person tone with precise vocabulary. The sentence that begins "But honestly" breaks all of that: it adds a personal aside, treats Earth as a person who "cannot take it anymore," uses vague phrasing like "kind of like" and "snapping," and ends with the emotional judgment "pretty scary." That mix of casual and emotional language is the clear weak point, so this is the best answer. The sentence defining how earthquakes occur is a strong, factual opening—reports are supposed to explain processes, so beginning with one is appropriate, not a weakness. The sentence about seismic waves traveling states a fact objectively; explaining what something does is exactly what informational writing should do, not storytelling. Naming "seismic waves" is also correct: precise, domain-specific vocabulary strengthens a science report rather than weakening it, so calling it too advanced misjudges what formal writing needs. Only the third sentence actually damages the formal style.

Question 15

1. The specific terms "coal" and "oil" and the definitions provided for each type of resource.
2. The casual words such as "things" and "stuff" and the personal phrase "I am going to be honest." (correct answer)
3. The pairing of short and simple sentences and the repeated use of the connecting word "and."
4. The examples of wind and sunlight and the general topic focus on energy resources.

Explanation: The correct choice names two features that break a formal explanatory style. The vague words "things" and "stuff" are too imprecise for academic writing, where terms like "resources" or "energy sources" belong. The phrase "I am going to be honest" is a first-person aside that shifts from objective explanation to personal commentary, breaking the neutral tone an essay needs. The choice about "coal" and "oil" and their definitions is wrong because naming specific terms and defining them is exactly what strong explanatory writing should do—these are strengths, not informal errors. The choice about short, simple sentences and repeated "and" points to real features of the draft, but sentence length is not what makes the tone informal; formal writing can use short sentences, and simply connecting ideas with "and" is a style issue, not a register problem the question asks about. The choice about wind, sunlight, and the energy topic is wrong because concrete examples and a clear topic focus are appropriate and helpful in explanatory writing—they do not lower the formality. Only one choice identifies two genuine markers of informal register: imprecise casual vocabulary and a personal interjection.

Question 16

1. The water cycle is a fascinating natural process that shows how our planet reuses the same water again and again through several amazing stages.
2. The water cycle explains how water first rises upward into the sky, then eventually falls back down toward the ground, and repeats this pattern many times.
3. The water cycle describes the continuous movement of water through evaporation, condensation, and precipitation, which transfers water between Earth's surface and the atmosphere. (correct answer)
4. The water cycle involves water heating up and moving into the air above, which then comes back down as it goes around and keeps working in this way.

Explanation: The best revision states the process objectively and uses precise scientific vocabulary: it names "evaporation, condensation, and precipitation" and describes water being transferred between "Earth's surface and the atmosphere." This keeps a third-person, informative tone with no opinion or vague wording, which is exactly what a formal explanatory style requires. The choice calling the cycle "a fascinating natural process" with "amazing stages" injects emotional, evaluative language that does not belong in objective explanatory writing. The choice describing water that "rises upward into the sky" and "falls back down toward the ground" stays vague and everyday rather than using the correct technical terms, so it does not sound academic. The choice saying water "comes back down as it goes around and keeps working in this way" relies on loose, conversational phrasing instead of precise vocabulary. Each of these keeps the general meaning but fails to maintain the precise, objective, academic style the question asks for.

Question 17

1. Version 2, because its everyday word choices, such as "rulebook" and "bossy," make ideas approachable and keep the reader comfortable with the topic.
2. Version 1, because it uses precise vocabulary, an objective tone, and complete sentences without slang or personal commentary. (correct answer)
3. Version 2, because its direct statement that the Constitution is "really important" adds an emphatic tone that most explanatory writing depends on.
4. Version 1, because it addresses the reader personally and expresses the writer's feelings about why the document matters most.

Explanation: The best answer is Version 1, because it uses precise vocabulary, an objective tone, and complete sentences without slang or personal commentary. Formal explanatory style keeps the focus on the topic, names things exactly ("legislative, executive, and judicial branches," "amendments"), and reports information neutrally. The choice praising Version 2's everyday words like "rulebook" and "bossy" is wrong because casual, imprecise language weakens formality rather than improving it. The choice claiming Version 2's "really important" adds a needed emphatic tone is wrong because formal explanatory writing reports facts objectively and avoids the writer's opinion. The choice saying Version 1 addresses the reader and shares the writer's feelings misdescribes Version 1, which stays third-person and objective; adding personal feelings would actually make writing less formal. Only the answer about precise vocabulary, objective tone, and complete sentences correctly identifies what maintains a formal explanatory style.

Question 18

1. A lever is a rigid bar that pivots on a fulcrum, and you can push down on one side to lift heavy stuff on the other side more easily.
2. A lever is a simple machine consisting of a rigid bar that pivots on a fulcrum; applying force to one side of the fulcrum can move a load on the other side by providing mechanical advantage. (correct answer)
3. I will explain how a lever works: a rigid bar pivots on a fulcrum, and when you push down on one side, the load on the other side rises upward.
4. A lever is a kind of rigid bar that pivots on a fulcrum, which is a really clever setup because it makes lifting heavy objects feel much easier.

Explanation: The best revision keeps a third-person, objective focus and uses precise technical vocabulary throughout—'simple machine,' 'rigid bar,' 'fulcrum,' 'applying force,' 'load,' and 'mechanical advantage.' It presents the information neutrally as fact, with complete, sophisticated sentences and no contractions or casual words. That combination fully meets the formal explanatory style the stem asks for. The option beginning 'A lever is a rigid bar that pivots on a fulcrum, and you can push down...' starts with technical terms but slips into second person ('you') and the casual word 'stuff,' breaking the objective, precise register. The option beginning 'I will explain how a lever works' uses correct terminology but announces itself in first person ('I will explain'), which is a subjective, conversational move that a formal explanation avoids. The option beginning 'A lever is a kind of rigid bar...' also uses technical terms but adds the vague hedge 'a kind of' and the subjective, emotional phrasing 'a really clever setup' and 'feel much easier,' which is opinionated rather than objective. Only one revision stays fully formal—objective point of view, precise vocabulary, and neutral tone from start to finish.

Question 19

1. No, because a formal science explanation should define each technical term the moment it appears so that any reader can follow the process without background knowledge.
2. No, because a formal science explanation should add a sentence stating why the topic matters to the reader personally to keep the writing engaging.
3. Yes, because it stays in third person, chooses precise vocabulary, and keeps an objective tone while explaining the process clearly. (correct answer)
4. No, because a formal science explanation should use shorter, simpler sentences instead of the longer combined sentences the writer uses here.

Explanation: The paragraph does exactly what formal explanatory writing calls for, so the best answer is the one saying the style is appropriate because it stays in third person, uses precise vocabulary, and keeps an objective tone. Every sentence focuses on the topic rather than on a narrator, and terms like "trachea," "alveoli," and "diffuses" are the correct, precise words for a science explanation. The choice claiming each technical term must be defined the instant it appears is wrong: formal explanatory writing may use accurate domain vocabulary without pausing to define every word, so the term use here is a strength, not a flaw. The choice claiming the writer should add a personal reason the topic matters is wrong: formal explanatory writing keeps an objective focus on the process and avoids personal appeals to the reader. The choice claiming the sentences should be shorter and simpler is wrong: combining related steps into a clear complex sentence ("oxygen diffuses into the bloodstream while carbon dioxide diffuses out") is appropriate and effective for explanatory writing. Because all three criteria in the correct answer are met, only that choice fits.

Question 20

1. The water cycle describes how solar energy heats water, lifts it into the sky, and eventually returns it to the ground as rainfall over time.
2. The water cycle involves evaporation, condensation, and precipitation, which move water through Earth's atmosphere and surface systems. (correct answer)
3. The water cycle sustains all living things on the planet because organisms cannot survive without a continuous supply of fresh water resources.
4. The water cycle transfers water from oceans into the air and then delivers it back to the land, keeping the whole planet supplied.

Explanation: The best revision states the process objectively and names the precise scientific terms—evaporation, condensation, and precipitation moving water through the atmosphere and surface systems. This is exactly what formal explanatory writing requires: accurate domain vocabulary and a factual, third-person tone. The option about solar energy lifting water and returning it as rainfall reads formally, but it relies on general descriptions ("lifts it into the sky," "as rainfall over time") instead of the correct technical terms, so it is less precise than the keyed answer. The option saying the cycle sustains all living things stays in third person and avoids slang, but it shifts into an emphasis on importance rather than explaining the actual process—it explains why water matters, not how the cycle works. The option describing water moving from oceans to air and back to land keeps a formal tone but ends with a vague, casual claim ("keeping the whole planet supplied") and still avoids the precise stages of the cycle. Only the keyed answer combines objective tone with the exact, correct scientific vocabulary the task asks for, so it is the strongest formal explanation.