Dr. Tubs developed a 7-step treatment plan for weight loss. Because of the success of this treatment plan it became a standard part of the education of all graduate clinical psychology students

However, many of these students, after completing their education and setting up their own private practice, modified this treatment plan as they continued to treat obese individuals. Although the 7-step treatment plan was slightly modified in many ways by many different clinical psychologists, it was still very effective for weight loss. This treatment plan

a. was probably not very effective because the success of the plan was dependent on the skill of the therapist to motivate the client.
b. had dependent variable validity.
c. had treatment outcome validity because it worked regardless of how it was changed.
d. had internal validity because it worked regardless of how it was changed.

C