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: Surgery
[{'content': 'Major mineral of the bone is \nSelect and explain. \nA. Calcite, B. Hydroxyapatite, C. Calcium oxide, D. Calcium carbonate', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Hydroxyapatite Hydroxyapatite crystals are the major mineral of bone Hydroxyapatite (also k/a bone mineral) is the salt of calcium and phosphorus with the formula Calc(PO4)6(01)2. Structural composition of bone : Also know Bone has to be 50% mineralised to be visible on radiographs.', 'role': 'assistant'}]