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': '"Myxoma" of Hea commonly arises from: \nSelect and explain. \nA. Left ventricl, B. Left atrium, C. Right ventricle, D. Right atrium', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Left atrium', 'role': 'assistant'}]