Kaplan's Explanation -
Read the Original Sentence Carefully, Looking for Errors:
When the underlined portion of the sentence contains a pronoun, check to make sure the pronoun agrees in number with the noun it is referring to.
Here, the underlined portion starts with the pronoun "they," which is referring to "the wolf."
Since "the wolf" is singular, it requires a singular pronoun. "They" is plural, however, and so is incorrect.
The sentence also uses the present progressive verb "are being eradicated" to describe an action that has taken place "for centuries," meaning it has happened in the past. This is also an error.
Scan and Group the Answer Choices:
(A) and (B) contain the incorrect plural pronoun "they."
(C), (D), and (E) change the pronoun to "it" or "its."
Eliminate Wrong Answer Choices:
Based on the error spotted during the initial reading of the sentence, (A) and (B) can be eliminated. They both use the wrong pronoun.
(C) corrects the pronoun error by changing "they" to "it." However, the past perfect verb tense, "had been eradicated" and "had been much maligned," is overly complicated and changes the meaning of the sentence, which states the wolf is maligned today. Eliminate (C). (E) is wrong because it ends up creating a clause beginning with "although" that does not include a verb. Dependent clauses beginning with "although" must contain a subject and verb. Here's an example: Although Jim is quiet, he is not shy. (D) corrects the pronoun error by using "it" and changes "they are being " to the simple past tense "it was," which works perfectly. (D) is correct.
TAKEAWAY: Pronouns are often tested. Stick to the rules—pronouns must have clear antecedents and agree in number with their antecedent—and watch out for answer choices that fix the pronoun error but introduce new errors.