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': 'Standard site for primary bone graft -a) Pelvisb) Greater trochanterc) Medial malleolusd) Lateral melleoluse) Fibula \nSelect and explain. \nA. a, B. b, C. ab, D. ae', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Standard site for primary cancellous bone graft → Iliac crest of pelvis.\nStandard site for primary cortical bone graft → fibula.', 'role': 'assistant'}]