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: Radiology
[{'content': "'Onion peel' appearance on radiograph is seen in: \nSelect and explain. \nA. Giant cell tumor, B. Ewing's sarcoma, C. Osteogenic sarcoma, D. Multiple myeloma", 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. Ewing's sarcoma", 'role': 'assistant'}]