Answer:
b. Whether or not relaxation exercises may cause alleviation of symptoms of test anxiety.
Explanation:
Dr. Prather randomized students who experience anxiety before exams, therefore<em> the idea isn´t to know how effective the waiting time is since otherwise</em>, he would have done an exercise about the waiting time mainly (a).
The problem is not how students behave anxiously before exams, <em>rather if relaxation exercises can help reduce anxiety. </em>(C )
The fragment only mentions students with anxiety, <em>doesn´t refer to other mood disorders</em> (d)
Therefore, according to the results, Dr. Prather will have evidence of whether relaxation exercises may or may not cause alleviation of symptoms of test anxiety, by making a comparison between students who received training in relaxation exercises and those who were in the waiting area and therefore didn´t receive the training.