The correct answer is a.: specific.
This structure (this +adj) requires an adjective and the only adjective is in a., the other options are verbs or nouns and are not correct.
During those months Rachel's mother looked after Aaron with something close to genuine fondness-- not pity, not obligation-- as though Aaron had become the son she always wanted.
This sentence flows very nicely and also makes sense. You can see that the punctuation is proper, the sentence makes sense, and the grammar is correct. With that in mind, that it the correct sentence structure.
which aspects of the topic to discuss
