Invigorate means fill with health and energy, as you may be able to work out from the "in-" prefix, which is here not functioning as a negative one but instead one meaning to take in, and "vigor," which means energy or liveliness. "Energy" is the closest synonym amongst the provided answer choices.

A "circumference" is the length of a line that goes around something or that makes a circle or other round shape or the outer edge of a shape or area. We can get this meaning from the prefix "circum-," which usually means around, as in the word "circumnavigate," which means go around something. A "perimeter" is the outside edge of an area or surface, so it is the answer choice closest in meaning to "circumference."

"Innovative" is an adjective that means original and unprecedented. Of the answer choices, the word with the closest meaning is "new."

The prefix omni- means everywhere or everything, as in “omnipotent,” which means all-powerful or “omniscient,” which means all-knowing. The word “omnipresent” means present everywhere; this is closest in definition to “ubiquitous,” which means existing everywhere. To provide further help, a “carnivore” is a creature that only eats meat; an “omnivore” is a creature that eats meat and vegetables, that eats everything.

"Malevolent" means wicked or evil; it is the antonym of benevolent. For clarification, "pious" means deeply religious; "dormant" means asleep or in a state of inactivity.

An animal which is “omnivorous” is an animal that eats both other animals and plants. To help, "omni-"usually means all when it is used as a prefix. From this, we can tell that “omnivorous” means all-eating or all-devouring. "Encompassing” means including or covering, so it is wrong. If you are all-knowing you are said to be “omniscient.”

"Bellicose" means eager to fight. "Amenable" and "affable" mean agreeable and likable, respectively. You can eliminate them because they have such similar meanings. "Tranquil" and "serene" both mean peaceful, so you can eliminate them. Or, if you know that the Latin root "belli-" means war, you may be able to figure out that "bellicose" means war-like. "Militant" means aggressive, therefore it has the closest meaning to "bellicose."

To “pontificate” is to speak about something in a way that shows you think you are always right. The word comes from the root “pontiff” meaning pope, so it means to talk like the Pope. If you “sermonize,” then you give advice on moral behavior to someone. To clarify the other terms, “harmonize” is to combine in a pleasing way; to “despise” is to hate.

The root "anthro"means related to mankind, and the root "phil­"means loving. The word “philanthropic” thus means something related to loving mankind. Of the five answer choices, something that suggests a love of man is “charitable.” Both “philanthropic” and “charitable” are used to describe someone who gives generously to others. None of the other answer choices are close in meaning to "philanthropic": “insolent” means rude; “bemused” means perplexed or confused; and “parsimonious” means selfish or not generous with others.

"Abbreviate" is a verb derived from the Latin root brevis, meaning short. "Shorten" is a verb with the same meaning, so it is the correct answer.