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': 'Severity of mitral stenosis is assessed by: \nSelect and explain. \nA. Loud opening snap, B. Length of murmur, C. Loud S1, D. Splitting S2', 'role': 'user'}, {'content': "Answer: B \nExplanation: Answer is B (Length of murmur) 'The duration of murmur correlates with the severity of stenosis - Harrison Features suggesting severe MS are : Proximity of S2 - O.S. gapQ,and Longer duration of mid-diastolic murmur Q", 'role': 'assistant'}]