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 is more characteristic of \nSelect and explain. \nA. Osteosarcoma, B. Osteoclastoma, C. Ewings sarcoma, D. Metastasis', 'role': 'user'}, {'content': "Answer: C \nExplanation: Onion peel appearance is a periosteal reaction more characteristic of Ewing's sarcoma.", 'role': 'assistant'}]