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: Radiology
[{'content': 'Base of hea is formed by \nSelect and explain. \nA. Rt. ventricle, B. LV, C. LV + RV, D. RA + LA', 'role': 'user'}, {'content': 'Answer: D \nExplanation: D i.e. RA + LA The base of hea forms its posterior surface. It is formed mainly by the left atriumQ and by small pa of right atriumQ.', 'role': 'assistant'}]