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
A variant of Giant cell tumor is? 
Select and explain. 
A. Ossifying fibroma, B. Non ossifying fibroma, C. Osteosarcoma, D. Chondroblastoma
D: Chondroblastoma
Answer: D: Chondroblastoma 
Explanation: 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).