It's a weakening question. We need to weaken the conclusion by saying that the policy of closing the borders and not issuing visas won't help out.

A. Drug X emits a faint smell that makes it very difficult for trained canines to identify at border control points. - Out of scope

B. The detrimental side effects of drug X only become visible after several years of usage. - Time duration is not relevant to the question asked

C. Andovia is surrounded on three sides by water, but has an excellent naval border police force. - Out of scope

D. Drug X resembles several other designer drugs currently on the market. - On the market, where? No mention of this. Out of scope.

E. Drug X is very easy to extract chemically from certain consumer products and is taken in droplet size doses that can easily be camouflaged as items such as hairspray or nail polish remover. - Yes. It says that even if the borders are closed, there are other ways to smuggle the drug.

Answer E