You are answering a USMLE-style medical question. Question: A 35-year-old woman comes to the physician because of intermittent episodes of heart palpitations for 3 weeks. The palpitations are accompanied by chest pain that is sharp and localized to the left 3rd intercostal space. The patient does not smoke. She drinks one to two glasses of wine on the weekends. She appears nervous. Her pulse is 110/min and irregularly irregular, and blood pressure is 135/85 mmHg. Examination shows a fine tremor on both hands and digital swelling. There is retraction of the left upper eyelid. A systolic ejection murmur is heard along the right upper sternal border. The extremities are warm, and pulses are 2+ bilaterally. Which of the following is the most appropriate pharmacotherapy? Options: A) Propranolol B) Digoxin C) Amiodarone D) Warfarin Reply with ONLY the letter of the correct answer (A, B, C, or D). No explanation.