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': 'Reumatic activity involves mostly valves- \nSelect and explain. \nA. Aortic & tricuspid, B. Aortic & pulmonary, C. Mitral & tricuspid, D. Mitral & aortic', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]