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': 'True about third heart sound is -a) Absent in Chr. constrictive pericariditisb) Absent in aortic aneurysmc) Absent in MSd) Normal physiologically in Athletes \nSelect and explain. \nA. ab, B. bc, C. bd, D. cd', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]