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': 'The commonest tumor of the myocardium is : \nSelect and explain. \nA. Myxoma, B. Rhabdomyoma, C. Sarcoma, D. Fibroma', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Answer is A (Myxoma) The commonest tumor of myocardium is a myxoma.', 'role': 'assistant'}]