The most common, and highly successful, therapy for phobia relies on

A) understanding the unconscious motivations behind the fear.
B) explaining to the person why the fear is irrational.
C) punishing the person for any attempt to avoid the object.
D) gradual exposure to the feared object.

Gradual exposure therapy (also known as systematic desensitization) is the most common and highly successful therapy for phobias. It involves gradually exposing the person to the feared object or situation, while teaching them coping skills to manage their anxiety. This gradual exposure helps to reduce the fear response and increase the person's confidence in facing their fear. Options A and B may be useful in therapy but are not the primary approach for treating phobias. Option C is not a recommended or effective approach for treating phobias.