Thanks for the question! So let’s take a look at this stimulus. We’re told that sugar consumption might exacerbate ADD in kids. A recent study found that kids produce lots of adrenaline after eating lots of sugar. The increase is especially noticeable if the source of sugar is candy, which doesn’t ameliorate the sugar’s effects by the ingestion of other foodstuffs.
Now we’re asked for an assumption on which the argument depends; in other words, this is a strengthen with necessary premise question. We can use the negation test. Take a look at (B), which tells us that overproduction of adrenaline causes ADD in children. Does this have to be true? Could this argument still stand if adrenaline doesn’t cause ADD in children? Yes, it could. Remember, the stimulus talks about the exacerbation of ADD, not the causing of it. So (B) is kind of off topic.
(D), on the other hand, tells us that the argument has to assume that increased adrenaline production can make ADD more severe in children. Well, what if it can’t? Then the argument falls apart. Note here that (D) uses the “make ADD more severe” (exacerbate) language, and not the “cause” language.
Hope this helps! Feel free to ask any other questions that you might have.