You are answering a USMLE-style medical question. Question: A 30-year-old woman presents to the emergency department with a recent episode of chest pain. She says she was previously well and denies any history of similar symptoms. She reports that, at onset, she felt as if she was going to die and says her heart beating has been beating really fast. There was also profuse sweating, and she says she feels short of breath. She could not recall how long the event lasted but can remember that the symptoms did go away on their own by the time she arrived at the emergency department. Her vitals rapidly returned to normal while giving her medical history and she begins to look and act more calm. No significant past medical history or current medications. Physical examination is unremarkable. Her electrocardiogram and initial cardiac enzymes are normal. Which the following is necessary to confirm the most likely diagnosis in this patient? Options: A) 1 month of associated symptoms B) Disruptive events lasting > 30 minutes on 2 separate occasions C) Family history D) Agoraphobia Reply with ONLY the letter of the correct answer (A, B, C, or D). No explanation.