Both (B) & (E) strengthen the argument.
(A) & (D) are irrelevant. Thus only C remains.
If the plant contains narcotics then it is this rather than the caffeine which disrupts the people's ability while doing their tasks.
(A) & (D) are irrelevant. Thus only C remains.
If the plant contains narcotics then it is this rather than the caffeine which disrupts the people's ability while doing their tasks.
