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
Osteosarcoma is differentiated from myositis ossificans by radiology by: 
Select and explain. 
A. Location, B. Absence of osteomyelitic changes, C. Shape of swelling, D. Peripheral field of differentiation
D: Peripheral field of differentiation
Answer: D: Peripheral field of differentiation 
Explanation: Ans. Peripheral field of differentiation