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': 'A variant of Giant cell tumor is? \nSelect and explain. \nA. Ossifying fibroma, B. Non ossifying fibroma, C. Osteosarcoma, D. Chondroblastoma', 'role': 'user'}, {'content': 'Answer: D \nExplanation: GCT is adult counterpart of chondroblastoma. Chondroblastoma is an epiphysis tumor which occurs in the 2nd decade (10-20 years), while GCT is an epiphysis tumor which occurs in adults (20 - 40 years).', 'role': 'assistant'}]