A researcher conducts a study to compare the effectiveness of different treatments for generalized anxiety disorder. Each participant receives behavioral therapy for two months, then cognitive therapy for two months, and finally cognitive-behavioral therapy for two months. At the end of each two-month period, a different therapist rates each participant's levels of generalized anxiety disorder. The results showed that cognitive-behavioral therapy was the most effective, followed by cognitive therapy, followed by behavioral therapy. Use this scenario to respond to each of the following questions.

A. What is the independent variable? Name the IV and the levels of the IV.

B. What is the dependent variable?

C. What is the confound variable?

D. How might the confound variable influence the results of the study in an undesirable way?

E. How could the confound be fixed?