A 23-year-old woman arrives at the emergency room complaining that, out of the blue, she had been seized by an overwhelming fear, associ-ated with shortness of breath and a pounding heart. These symptoms lasted for approximately 20 minutes, and while she was experiencing them, she feared that she was dying or going crazy. The patient has had four similar episodes during the past month, and she has been worrying that they will continue to recur. Which of the following is the most likely diagnosis?

A. Acute psychotic episode

B. Hypochondriasis

C. Panic disorder

D. Generalized anxiety disorder