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: Surgery
[{'content': 'Expansile lytic osseous metastases are characteristic of primary malignancy of \nSelect and explain. \nA. Kidney, B. Bronchus, C. Breast, D. Prostate', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e. Kidney", 'role': 'assistant'}]