To help him overcome his fear of flying,Duane's therapist has him construct a hierarchy of anxiety-triggering stimuli and then learn to associate each with a state of deep relaxation. Duane's therapist is using the technique called

A) systematic desensitization.
B) aversive conditioning.
C) shaping.
D) free association.

The technique being described involves gradually exposing the individual to fear-triggering stimuli while simultaneously promoting relaxation, which is the basis of systematic desensitization. Aversive conditioning involves associating negative consequences with undesired behavior, shaping involves reinforcing successive approximations of a behavior to teach it, and free association is a technique used in psychoanalytic therapy to explore unconscious thoughts and experiences.