Evaluating the effectiveness of psychotherapy is complicated and diffi-cult because: A. disorders sometimes clear up on their own. B. different approaches to treatment pursue entirely different goals....

Evaluating the effectiveness of psychotherapy is complicated and diffi-cult because:

A. disorders sometimes clear up on their own.

B. different approaches to treatment pursue entirely different goals.

C. clients’ problems vary in severity.

D. all of the above are involved.