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': 'In which of the following cases, apical diastolic murmur occur: \nSelect and explain. \nA. Mital regurgitation, B. Mitral stenosis, C. Aortic stenosis, D. Ventricular septal defect', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]