This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Bone Tumour, Subject name: Orthopaedics
[{'content': "Most common primary bone tumour in adult bone is: \nSelect and explain. \nA. Chondro sarcoma, B. Osteogenic sarcoma, C. Admintinoma, D. Ewing's sarcoma", 'role': 'user'}, {'content': "Answer: B \nExplanation: (osteogenic sarcoma) (218-M) (185-Appley's 8th)* Osteogenic sarcoma is highly malignant primary bone tumour - (Common in Age 15-25 years)* Osteoid osteoma - is the commonest true benign tumour of the bone.", 'role': 'assistant'}]