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': 'Patchy calcification is the x-ray feature of bone tumor \nSelect and explain. \nA. Osteosarcoma, B. Chondroblastoma, C. Fibrous dysplasia, D. Osteoclastoma', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]