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
[{'content': 'Commonest site of occurrence of chondroblastoma \nSelect and explain. \nA. Pelvis, B. Femur, C. Ribs, D. Proximal tibia', 'role': 'user'}, {'content': 'Answer: D \nExplanation: 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', 'role': 'assistant'}]