Research Comparing the Effectiveness of Psychotherapists Who Received Training in a Number

Research comparing the effectiveness of psychotherapists who received training in a number of different areas (psychology, psychiatry, counseling, social work) has demonstrated

A) psychologists and psychiatrists tend to be more effective than counselors and social workers.
B) clinical psychologists tend to be more effective than psychiatrists.
C) psychiatrists tend to be more effective than clinical and counseling psychologists.
D) no reliable association exists concerning therapists' professional training and effectiveness.