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
Not a diaphyseal tumor 
Select and explain. 
A. Adamantinoma, B. Chondroblastoma, C. Osteoid osteoma, D. Ewing's sarcoma
B: Chondroblastoma
Answer: B: Chondroblastoma 
Explanation: None