Answer:
The correct pronoun is whomever.
Explanation:
The pronoun whomever is the <em>objective case</em> of whoever. This means whomever can only be used either with a preposition (e.g. to, for, or about) or with a verb (an action word) that requires a direct object. Use whoever or whomever to agree with the verb in that dependent clause, regardless of the rest of the sentence.
White is lighthearted, while thoreau is thought provoking.
I believe that the answer Is D
I believe the answer is A.) However because it is used to show how petroleum is different than coal which is a contrast.