Adverbs modify (describe) verbs or other adverbs and often end in -ly. You need to locate the verb to determine at least one of the adverbs (the action of the sentence.) This is a complex sentence because it has an independent clause (it was not exactly what he had in mind) and a subordinate clause (when he agreed to do the task). If you just look at the independent clause, or the one that can stand by itself, you will find the verb 'was'. Ask yourself 'was what'. The answer is not, which means it is the adverb. To find the adverb describing it, we again ask, 'not what'. The answer is exactly. So the answer is A.
It should be D because it showing kind of negative message
Honestly, I don't think Daisy will end up with Tom or Gatsby. Each of them has a flaw that just cannot be ignored enough in a relationship. Tom is too controlling, which is hardly even a relationship at all, and Gatsby, despite his sweetness to her opposite of Tom, wants to do something even more impossible: relive the past, as if the past is a swimming pool to jump harmlessly right back in. What Gatsby is deluding is too good to be true and Tom's personality is too poor to be true, which is why that infatuation will not last very long either.