This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cardiac disorders, Subject name: Pathology
[{'content': 'Most common cause of mitral stenosis is: \nSelect and explain. \nA. Rheumatic hea disease, B. Infective-endocarditis, C. Diabetes mellitus, D. Congenital', 'role': 'user'}, {'content': 'Answer: A \nExplanation: The most frequent causes of the major functional valvular lesions are: Aoic stenosis: calcification and sclerosis of anatomically normal or congenitally bicuspid aoic valves Aoic insufficiency: dilation of the ascending aoa, often secondary to hypeension and/or aging Mitral stenosis: rheumatic hea disease Mitral insufficiency: myxomatous degeneration (mitral valve prolapse)', 'role': 'assistant'}]