Critical Reasoning

Scientists have created double-blind studies so that neither the subjects of the experiment nor scientists know whether the subject is receiving an actual drug or a placebo, which is nothing more than a sugar pill. Essentially, if one knows whether one is receiving actual medicine or a placebo, such knowledge can affect the outcome of a study. A recent double-blind study on the effectiveness of the Selective Serotonin Reuptake Inhibitor (SSRI) Freloxamine on depression found that those subjects administered the drug were 15% more likely to have a decrease in symptoms than the control group, which was comprised of those who received a placebo. Since neither group knew which they were receiving, the placebo or the SSRI, the observed drop in depression can only be attributed to Freloxamine.

Which of the following, if true, best calls into question the conclusion of the argument?

A) Neither the subjects nor the doctors in either group (the control group or the Freloxamine group) knew which drug they were receiving.
B) Since subjects in both groups were debriefed on the potential side effects of SSRI, which can often be pronounced, many in the Freloxamine group, upon exhibiting side effects, concluded that they were being administered the SSRI.
C) Freloxamine does not exhibit a uniform effect in all subjects, with many reporting little improvement in symptoms of depression, even after several months of taking the drug.
D) At dosages two-fold of those employed in the trial, Freloxamine has been shown to cause brief episodes of psychosis.
E) One subject from the Freloxamine group experienced debilitating side effects and was forced to drop out of the trial before its completion.

OA B

Source: Magoosh