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': 'All of the following hea sounds occur sholy after S2, EXCEPT: \nSelect and explain. \nA. Opening snap, B. Pericardial knock, C. Ejection click, D. Tumor plop', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Pericardial knock, Opening snap, and Tumor plop occurs sholy after S2. Ejection click occurs after S1.', 'role': 'assistant'}]