Ethical behavior by therapists is important because a. clients share personal information b. clients don't expect to get better during therapy c. therapy is ineffective d. therapy is complex

The correct option is D.
Ethical behavior by therapist is of utmost importance because during the course of their service therapists will face differing situations which require that they make almost instant decisions. The ethic guidelines which guide the behavior of practitioners will help the therapists to make the right decisions and to exhibit the right behavior in such situations.

D. Therapy is complex. Hope this helps you!