Two observations will help to answer this question. First, remove the subordinate clause "try as he will." This gives you: "The American can never imagine." You can immediately eliminate one option:

"The American can never imagines..."  (The helper verb "can" will take a verb form with no ending—not having the "s" on the end of "imagines.")

For the remainder, notice the pronoun agreement in the subordinate clause. You have:

American—he

American—they

Americans—he

The only option that is correct is the one that matches the two singular forms: American—he. So, the sentence is correct as it is written.

The pronoun "it" should be plural because its antecedent is the plural subject "resources." Only two choices correcty change "it" to "they," but one of them, "as they depend on the reduction of foreign oil," confuses cause and effect. The resources are not dependent on the reduction of foreign oil. The correct answer is "as they may reduce our dependence on foreign oil."

The sentence as written contains one small error. "It," a singular pronoun, is used to refer to the plural "sporting events." In order to fix this issue, the pronoun needs to be made plural, which is done in "Most men who go to sporting events find them an enjoyable diversion."

In this sentence, the subject is "anyone," a singular pronoun. Therefore, all pronouns relating back to "anyone" should be singular. In the underlined portion of the sentence, "preparing a plan that they stick to," "they" is plural, not singular. Now that we have identified the problem, we have to figure out how to correct it.

Given that "anyone" is gender neutral, the best way to improve this sentence is avoid the use of a gendered pronoun (meaning "he" or "she") and simply avoid using a pronoun at all. The correct answer, "preparing a plan and sticking to it," accomplishes this objective and is therefore the best way to improve the sentence.

The original sentence contains an error in noun-pronoun agreement: the plural possessive pronoun "their" is used to refer to "the worker," a singular noun. We need to use a singular possessive pronoun to refer to a singular noun, and our choices in this case are "his," "her," and "its." One doesn't use "its" to refer to people, and while "the worker" is not a gendered noun, we can tell that the worker being described in the sentence is male because of the use of the possessive pronoun "his" in the phrases "his lost green helmet" and "made his way home happily." For the sentence to be correct, we need to replace "their" with "his," so the correct answer is "Just as he finished work for the day, the worker found his lost green helmet and made his way home happily."

Choose a pronoun that properly agrees with the subject. In this case, "basketball team" is singular, although it represents a group of people, and should be accompanied with "its," instead of "their."

Whenever a sentence refers to a person of unknown gender and a singular possessive pronoun is required that refers to that person, one typically includes both the masculine and the feminine possessive pronouns in the phrase "his or her." In this case, "his or her" is a better choice than "their" because "student" is a singular noun, and "their," which is a plural pronoun, does not agree with it in number. Considering the other potential answer choices, "they're" is the contraction of "they are," which would not make sense in the sentence, "it's" is the contraction of "it is," which wouldn't make sense in the sentence either, and "its" is the possessive form of the pronoun "it," which is not used to refer to a person. So, none of those answer choices can be correct.

The original text contains a pronoun agreement error. The intended antecedent of the pronoun "it" is supposed to be "books," which is plural and would therefore require the plural pronoun "them" instead of the singular pronoun "it."

The only answer choices that contain "them" instead of "it" are "that cause them to decay" and "that causes them to decay." The answer choice with "causes," however, uses this singular verb with a plural subject, "materials," and is therefore incorrect.

The original text "the person who has most significantly transformed the world through their charitable actions or scientific discoveries" and the answer choice "the person who most significantly transformed the world through their charitable actions or scientific discoveries" contain pronoun agreement errors because they incorrectly use the plural pronoun "their" to refer to the singular noun "person."

The answer choices "the person that has most significantly transformed the world through his or her charitable actions or scientific discoveries" and "the person that significantly transformed the world through his or her charitable actions or scientific discoveries" are incorrect because they use "that" to refer to a person, when "who" or "whom" should be used when referring to a person. (Remember to use "that" only when referring to non-human living things or objects.)

The answer choice "the person who has most significantly transformed the world through his or her charitable actions or scientific discoveries" is correct because it is the only answer choice that correctly uses "who" and the singular pronoun "his or her" to match the singular noun "person."

The pronoun refers to employees, so the pronoun should be plural rather than the singular he or she.