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: Anatomy
Commonest site of occurrence of chondroblastoma 
Select and explain. 
A. Pelvis, B. Femur, C. Ribs, D. Proximal tibia
D: Proximal tibia
Answer: D: Proximal tibia 
Explanation: Most commonly involved bones are proximal tibia (most common) Femur and pelvis(2nd most common) Humerus Ribs Shoulder girdles Refer Campbells 12th /e p 914