The University Counseling Center Has Treated a Large Number of Students

Multiple Choice

The university counseling center has treated a large number of students for depression. They find that the standard deviation of depression scores for their pool of students is substantially higher after treatment than before treatment. The most likely explanation is

A) some students improved more than others.
B) some students improved substantially while others actually got worse.
C) depression therapy at the counseling center affects different students differently.
D) all of the above