The use of "fighting," a participle form, in the sentence makes the sentence not have a proper verb. To be a functional verb, the participle must be used with some form of the verb "to be." The only answer choice that does this is "The boys were fighting every single day for the past three weeks."

The non-underlined portion of the sentence, which is the main body, contains a past tense verb, "was." This means that the underlined portion, a dependent clause, must use the past tense as well. As it is written, the sentence currently contains a present tense verb, "has." The only answer choice that fixes this issue is "as he had a strong artistic side to his personality."

The use of "confuse" is incorrect, as it is a present tense, plural verb. As the subject of the sentence, "novel," is singular, and the main verb of the sentence, "was," is in past tense, so "confuse" should take on a past tense, singular form. The only answer choice featuring such a form is "The novel was a long rambling mess that often confused readers."

The use of the plural verb "receive" is incorrect. Even though the verb is next to the plural "runners," it refers to the singular subject, "fastest." The verb needs to be changed to be in agreement with the subject of the sentence. "The fastest of all the runners receives" is the only answer choice that does this, so it is the correct answer.

The underlined portion of the sentence includes a present tense verb, "remain," while the non-underlined portion of the sentence includes a past tense verb, "said." The two verbs must be in the same tense, as they describe action taking place at the same time. The only answer choice that corrects this issue is "but remained completely silent throughout."

The use of the present tense verb "talk" goes against the introductory clause in the sentence, which places the sentence's action in the past. The main verb of the sentence needs to be in the past tense. Therefore, the correct answer choice is "the two talked for hours and hours, staying up until dawn."

The use of the present tense verb "believes" in the underlined portion of the sentence is at odds with the main verb of the sentence, "made," which is in the past tense. "Believes" needs to be changed to the past tense form, making "that the sergeant believed he would never" the correct answer choice.

The sentence calls for the past tense of the verb "to boil" because it uses other past-tense verbs (like "made") to describe the action taking place.

The phrase "three years ago" indicates that the action of the sentence's action happened in the past. Despite this, the sentence is written with the present tense verb "deepens," leading to confusion with the timing of the sentence. "The mystery only deepened after the new evidence" is the only answer choice that features a past tense verb, so it is the only answer choice that clears up this confusion.

The use of the past tense verb "cleared" in the sentence is confusing and incorrect. "Cleared" is not the main verb in the sentence, and should take some other verbal form. Using the gerund, or a verb form that functions as a noun, the correct answer choice is "through the night clearing debris from the wreckage site."