In a Study of 100 People with Panic Disorder,50 Were

Multiple Choice

In a study of 100 people with panic disorder,50 were treated with psychotherapy and 50 were treated with medication.At the end of 12 weeks of treatment,the psychotherapy group had an average score of 25 on a scale of panic severity,while the medication group had an average score of 75.This difference is called the

A) within-groups variance.
B) experimental effect.
C) internal validity.
D) None of the above