This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Anatomy and physiology of bone and fracture healing, Subject name: Orthopaedics
[{'content': 'The bone matrix has the following crystals \nSelect and explain. \nA. Calcium hydroxyapatite, B. Calcium pyrophosphate, C. Calcium phosphate, D. Calcium sulphate', 'role': 'user'}, {'content': 'Answer: A \nExplanation: The bone is made up of bone cells and extracellular matrix.The matrix consists oftwo types of materials,organic and inorganic. The organic matrix is formed by the collagen,which forms 30-35% of dry weight of a bone. The inorganic matrix is primarily calcium and phophorus salts,especially hydroxyapatite .It constitutes about 65-70% of dry weight of a bone. ref:maheswari,5th edition page no.9', 'role': 'assistant'}]