The goal of behavior therapy is to: A. identify the early childhood unconscious conflicts that are the source of the client's symptoms. B. achieve major personality reconstruction. C. alter the frequency of specific problematic responses by using conditioning techniques. D. alter the client's brain chemistry by prescribing specific drugs.

First, it is important to know what behavior therapy is. Behavior therapy is a type of psychotherapy that aims to change unhealthy behavior patterns by using learning principles, such as classical and operant conditioning.

Now, let's evaluate each option and determine which one accurately describes the goal of behavior therapy: A. Identifying the early childhood unconscious conflicts that are the source of the client's symptoms is not the focus of behavior therapy. This option is more related to psychoanalytic therapy, which focuses on unconscious conflicts and past experiences. B. Achieving major personality reconstruction is not the primary goal of behavior therapy. While behavior therapy can contribute to personality changes, it mainly focuses on altering specific problem behaviors. C. Altering the frequency of specific problematic responses by using conditioning techniques is consistent with the principles of behavior therapy. This option accurately describes the goal of behavior therapy. D. Altering the client's brain chemistry by prescribing specific drugs is not the focus of behavior therapy. This would be more related to pharmacotherapy or biological treatments for mental disorders.

Based on the evaluation of the options, the correct answer is: C. Alter the frequency of specific problematic responses by using conditioning techniques.