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: Pathology
[{'content': "Calcification of the aortic valve is seen in - \nSelect and explain. \nA. Aortic stenosis, B. Aortic regurgitation, C. Marfan's syndrome, D. Hurler's syndrome", 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]