Dr Noyd Conducted an Experiment to Determine Whether Talking to a Psychiatrist

Dr. Noyd conducted an experiment to determine whether talking to a psychiatrist made depressed people less depressed. He randomly divided participants who scored highly on a depressive inventory into two groups. Group A talked over their problems with a psychiatrist while Group B did nothing. He found that Group A showed significantly more improvement in their depression than did Group B. In Dr. Noyd's experiment, the experimental group refers to

A) the differences observed whether or not therapy was received.
B) the people who talked over their problems.
C) the scores on the depressive inventory.
D) the random assignment.