Problem: A 35-year-old woman with a history of generalized anxiety disorder and irritable bowel syndrome presents for an annual check-up. She tearfully states that she has been unable to go out with her friends because she gets "very scared and nervous" in crowds when taking the subway, in parking garages, and in large buildings. She states that her distress is so significant that she has not left her home in 6 months except to come to this appointment. She is not taking any medication, denies any other physical symptoms, and her vital signs and physical exam are unremarkable. What is the best next step in management? A. Group therapy B. Family therapy C. Pharmacotherapy D. Dialectical behavioral therapy