"dr. grant is conducting research on stress management. group a received progressive relaxation training prior to test taking, while group b received no training. group a is the while group b is the "

I believe the answer is: experimental group/control group

Experimental group refers to the group which is exposed to treatment that being tested by the researchers. Control group refers to the group that is not exposed to the treatment and would be used by the researchers as a benchmark to know whether the determine give unique effects.

can you explain it better

answer; mission;