This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: C.V.S, Subject name: Pathology
[{'content': 'Most common primary cardiac tumour? \nSelect and explain. \nA. Myxoma, B. Rhabdomyoma, C. Rhabdomyosarcoma, D. Angiosarcoma', 'role': 'user'}, {'content': 'Answer: A \nExplanation: * The most common primary tumour of the heart is myxoma. It constitutes 50% of all primary cardiac tumours.* Most common site is left atrium.* Most common tumour of heart is metastasis from lung cancer.* Most common tumour of heart valves is papillary elastoma', 'role': 'assistant'}]