I picked the correct answer D on this one, because it obviously addresses the issue well. However I put a huge question next to A, because it seems like a great answer as well. If there is a more effective medication that could explain why the people taking the less effective medication is 12 to 15% higher.
Of course this assumes that a number of people in the study are actually TAKING the new meds, but that does not seem like to large of an assumption to consider.
Is the problem with answer choice A this needed assumption? Or is there some other issue?
Thanks!