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: Surgery
[{'content': 'Most common primary bone tumour in adult bone is: March 2011 \nSelect and explain. \nA. Chondrosarcoma, B. Osteogenic sarcoma, C. Adamantinoma, D. Ewings sarcoma', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. B: Osteogenic sarcoma Of the primary bone malignancies, multiple myeloma is the commonest Osteosarcoma is the second most common, and a highly malignant primary bone tumour Osteosarcoma: Metaphyseal MC site: Lower end of femur Sunburst appearance Codman's triangle Pa:ient may present with metastasis to lungs Treefment: Chemotherapy + limb salvage surgery", 'role': 'assistant'}]