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
Site for 1st order bone grafting - 
Select and explain. 
A. Pelvis, B. Tibial metaphysis, C. Medial malleolus, D. Femoral condyle
A: Pelvis
Answer: A: Pelvis 
Explanation: Option a, b, c, d & e all can be used as a source of bone graft.
However, most common and primary source of bone graft is iliac crest of pelvis.