Which of the Following Is True of Systematic Desensitization

Which of the following is true of systematic desensitization?

A) Systematic desensitization involves two levels of exposure to a phobic object: conscious and unconscious.
B) In systematic desensitization, the therapist pairs operant conditioning with intensive exposure to a phobic object.
C) In systematic desensitization, the therapist generates a hierarchy of increasing contact with the feared object, ranging from mild to extreme.
D) Systematic desensitization is a rarely used application of behavior therapy that is not very effective in treating phobias.