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': 'Radiological feature of osteosarcoma is – \nSelect and explain. \nA. New bone formation, B. Sunray appearance, C. Cotton wool app., D. Osteoid formation', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]