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': 'The severity of mitral regurgitation is decided by all of the following clinical findings except \nSelect and explain. \nA. Presence of mid- diastolic murmur across mitral valve, B. Wide split second heart sound., C. Presence of left ventricular S3 gallop., D. Intensity of systolic murmur across mitral valve', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]