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': 'Osteosarcoma is differentiated from myositis ossificans by radiology by: \nSelect and explain. \nA. Location, B. Absence of osteomyelitic changes, C. Shape of swelling, D. Peripheral field of differentiation', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Ans. Peripheral field of differentiation', 'role': 'assistant'}]