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': 'Site for 1st order bone grafting - \nSelect and explain. \nA. Pelvis, B. Tibial metaphysis, C. Medial malleolus, D. Femoral condyle', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Option a, b, c, d & e all can be used as a source of bone graft.\nHowever, most common and primary source of bone graft is iliac crest of pelvis.', 'role': 'assistant'}]