The central issue here is not verb tense usage but, rather, incorrect pronoun usage. "Who's" represents the contraction of the pronoun and verb "who is." The correct possessive form of the pronoun who is "whose." All of the other answer choices do not address this issue.

"Themselves" is a referential pronoun, and the structure of the sentence would make it refer to "humans." For the sentence to make sense, the pronoun needs to indicate "domesticated animals" are the ones being provided for. "Providing for them" is the correct answer choice.

The use of "myself" is incorrect in the sentence, as it is a reflexive pronoun and needs the first person pronoun "me" to precede it. Therefore, "myself" must be changed to the first person pronoun "me," making the correct answer "been seen by me."

This sentence uses the wrong pronoun. The word "which" is never used for nouns which refer to humans. The correct choice here is "who." No other changes are necessary. Note that "that" does not begin a relative clause (in which case you would have to omit the commas), and the word "being" generally has to do with existence and is never used in this way. The correct choice is, "the teens, who were excited, bought much food."

The first underlined part can be broken apart into "you are," and calls for the use of the contraction "you're;." The second two cases are possessives, and call for the use of "your."

This sentence misuses the word "its," which is the possessive form of the word "it." It is clear from context, however, that the contraction, "it's" is necessary here. The correct choice is, "It's important to study every day." The other choices do not contain legitimate forms of the word "it."

This sentence misuses the word "it's," which is a contraction for "it is." The appropriate form here (the possessive) is "its," omitting the apostrophe. No additional changes are necessary. The correct choice is, "to have a problem with its transmission."

This sentence misuses the word "who." The pronoun "who" is reserved for humans only. All other things, whether living or not, is referred to as "which" in standard English. Note that "that" is inappropriate here because it would make the following phrase ("the company built") a part of the main clause, which would mean you would have to omit the commas. The same explanation applies to just omitting the pronoun. The correct choice is, "The robot, which the company built, was the first."

The use of "ourselves" is incorrect, as it is a referential pronoun, meaning that the word must refer to an earlier use of the first person plural pronoun. The use at the end of the sentence is the first one, and should not be a referential pronoun. "To us" is the correct answer choice.

This sentence contains a pronoun usage error. The word "who" is meant to refer to company, but is never use to describe non-human words. The appropriate choice is "which," making the correct choice "which was considered quite aggressive in the industry."