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: Orthopaedics
[{'content': 'Not a polyostotic bone lesions \nSelect and explain. \nA. Osteochondroma, B. Fibrous dysplasia, C. Multiple myeloma, D. Anuerysmal bone cyst', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]