In this argument we have a source that provides a conditional statement. We declare that this source is reliable. The sufficient condition is met, therefore the necessary condition will probably occur.
With answer choice A, the source (science journal) does not provide a conditional statement. It also says that if the data is accurate, the medication "must" be safe. In the stimulus, they did not reach such a level of certainty. They concluded that the necessary condition (rejection by committee) would "probably" occur.