What does research suggest about the comparative effectiveness of psychotherapeutic techniques? ch 16?

These are the choices I found on the internet:

a. A meta-analysis suggests that psychodynamic psychoanalysis is the least effective approach.

b. Data regarding the comparative effectiveness of psychotherapeutic techniques is unavailable.

c. No studies have found one psychotherapeutic approach more effective than another.

d. Research shows that cognitive-behavioral therapy is the most effective approach.

The answer is letter C - No studies have found one psychotherapeutic approach more effective than another.