The theory, which I have chosen for the given case of Mark is a cognitive-behavioral theory. The cognitive-behavioral theory (CBT) is described as psychotherapy focuses on changing thoughts and behavior problems. It applies principles derived from scientific research to address and modify human behavior. In addition, CBT is primarily concerned with the solution of current problems and second only to the understanding of their origin in the past. A good therapeutic relationship can be considered essential for psychotherapy effective cognitive-behavioral approach. Finally, it is possible to characterize the TCC to be active, directive, structured, and relatively short-lived. ...