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
The Radiological hallmark of Osteo SA- 
Select and explain. 
A. Soap bubble appearance, B. Sun ray appearance, C. Osteoid formation by neoplastic cells, D. Cotton wool appearance
B: Sun ray appearance
Answer: B: Sun ray appearance 
Explanation: 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*