This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Imaging of Musculoskeletal Tumors, Subject name: Radiology
[{'content': 'The Radiological hallmark of Osteo SA- \nSelect and explain. \nA. Soap bubble appearance, B. Sun ray appearance, C. Osteoid formation by neoplastic cells, D. Cotton wool appearance', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. is 'b' i.e. sunray appearance .X-ray features of Osteosarcoma.Area of irregular destruction of metaphysesErosion of the overlying cortex.New bone formation in the matrix of the tumor*Periosteal reaction* (which is irregular; periosteal reaction in osteomyelitis is smooth)Codman's triangle*Sun-ray appearance*", 'role': 'assistant'}]