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: Orthopaedics
[{'content': 'True regarding osteosarcoma is - \nSelect and explain. \nA. Occurs because of proliferation of osteoclasts, B. Sunray appearance in X-ray indicates new bone formation, C. Affects mainly males in 5th or 6th decade, D. Lymphtic metastasis is most common', 'role': 'user'}, {'content': "Answer: B \nExplanation: Osteosarcoma arises from primitive bone forming cells.\nSunray appearance and Codman's triangle indicate periosteal new bone formation.\nOsteosarcoma occurs in childhood or young adult (10-25 years).\nBlood metastasis is most common (not lymphatic).", 'role': 'assistant'}]