This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Bone Tumour, Subject name: Orthopaedics
[{'content': 'Onion peel appearance in X-ray suggest: \nSelect and explain. \nA. Osteogenic sarcoma, B. Ewing sarcoma, C. Osteoclastoma, D. Chondrosarcoma', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans: b (Ewings sarcoma)Ref: Maheshwari Ortho, 3rd ed, p. 222, T 30.5', 'role': 'assistant'}]