You have symptoms, so in your head you come up with the diagnosis (in our example, hypoalphalipoproteinemia). Once you have that diagnosis, you have to know what drug you use to treat it (niacin). Once you've figured out (read: remembered; there's clearly no actual reasoning through it) the drug, you have to remember its main side effects (facial flushing). And finally, once you have the side effects straight, you have to remember what other drug you can use to treat those side effects (aspirin).
You can know 3 out of 4 of those facts, and the world may never know it, because you're still going to get that question wrong. And that is why these questions are so confidence-depleting and soul-sucking.