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
The bone matrix has the following crystals ? 
Select and explain. 
A. Calcium hydroxyapatite, B. Calcium pyrophosphate, C. Calcium phosphate, D. Calcium sulphate
A: Calcium hydroxyapatite
Answer: A: Calcium hydroxyapatite 
Explanation: Ans. is 'a' i.e., Calcium hydroxyapatite Structure of bone Bone is a specialized connective tissue. o Bone components are :? Inorganic elements (65%) Organic matrix (35%) 1. Inorganic elements It is the mineral phase, principally composed of calcium and phosphate, mostly in the form of hydroxyapatite.