This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Upper Limb Traumatology, Subject name: Orthopaedics
[{'content': 'In myositis ossificans mature bone is seen: \nSelect and explain. \nA. At periphery, B. In center, C. Whole muscle mass, D. In the joint capsule', 'role': 'user'}, {'content': 'Answer: A \nExplanation: In myositis ossificans, there is peripheral ossification and central lucency of the mass Osteosarcoma- growth in to out Myositis ossificans- growth out to in I.O.C is CT SCAN The mass is usually separated from underlying bone by at least a thin line', 'role': 'assistant'}]