The correct answer will resolve the redundant relative pronoun that, replacing it with the definite article "the". Using the article "a" is problematic precisely because the article refers to a definite noun "the number of people...". The other answer choice that attempt to implement a subordinating conjunction all result in issues with awkward syntax.

This sentence misuses the word "who's," which is a contraction for "who is." The context of this sentence dictates that the possessive form of the word be used here. The correct choice is "whose." The other choices are not actual forms of this word.

This sentence misuses the pronoun "his." Since a man is not mentioned anywhere in the sentence, it makes no sense to use the word "his." Most likely, it is Sharon's project that is meant here, meaning that "her" should be used. Note that "hers" is not a proper word. The correct choice is "her."

This sentence contains an error in the usage of "it's," which is a contraction for "it is." The context of the sentence makes it clear that the possessive pronoun is needed here, which is "its," without the apostrophe. Note that "that" is not specific enough (could be referring so some other battery), and "the car's/of the car" is redundant, given the first half of this sentence. The correct choice is, "he tried changing its battery."

This sentence uses the wrong form of "it." When the apostrophe is present (it's), the word is a contraction for "it is." The possessive form, which is needed here, is "its" (without the apostrophe). No additional punctuation or other changes are necessary - colons are never used to split up a clause. The correct choice is, "its latest project to Tim."

The possessive pronouns "hers," "his," "yours," "its," "ours," and "theirs" are never used with apostrophes. The correct version of this sentence reads: "I was fairly certain that the handbag was mine, but she insisted it was hers."

This sentence misuses the pronoun "it's," which is a contraction for "it is." The correct form (the possessive) is "its," without an apostrophe. The correct choice is, "Rome because she was enamored with its history." No additional punctuation is necessary. The word "because" does not take a comma before it when joining clauses.

This is an error of inconsistent usage. "Students" does not clearly match up with "our." The speaker needs to identify himself in both words—"we and our" or "students and their."

The answer choice "one must consider the time period in which it was written" is correct because it contains the word "one," which matches the word "one" used in the first clause of the sentence.

All of the other answer choices are incorrect because they contain the pronoun "we," and therefore lead to pronoun agreement errors.

The original text contains a pronoun consistency error. The underlined portion of the sentence contains the pronoun "we," but the sentence uses "one" before that. In order to maintain consistency, the underlined portion should use "one" rather than "we."

The answer choice "one had first accounted for" contains a tense error, even though it correctly uses "one" instead of "we."

The answer choice "one must first account to" is incorrect because the correct idiom is "account for."