Which of the following is not a common theme of the many schools of psychotherapy?

A) self-knowledge
B) interpersonal learning
C) emotional defusing
D) use of drugs
E) use of a step-by-step process

The use of drugs is not a common theme of psychotherapy. While some types of psychotherapy may incorporate medication as part of the treatment plan (such as cognitive-behavioral therapy for depression which may include antidepressant medication), the use of drugs is not a central feature or theme of psychotherapy itself. Common themes of psychotherapy include self-knowledge, interpersonal learning, emotional regulation, and a step-by-step process of change.