This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Medicine
[{'content': 'A 35 year old athlete has height 184 cm., arm span 194cm., pulse rate 64/min., BP 148/64 mm Hg. Chest ausultation reveals long diastolic murmur over right 2nd intercostal space on routine examination.The probable diagnosis is - \nSelect and explain. \nA. Aortic regurgitation, B. Atrial septal defect, C. Ebstein anomaly, D. Coarctation of aorta', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]