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': 'Bone resorption markers are - \nSelect and explain. \nA. Serum propeptide of type I procollagen, B. Osteocalcin, C. Urine total free deoxypyridinoline, D. Free glutamic acid cross linkage', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Markers of bone resorption\n\nUrine & serum cross-linked\xa0N telopeptide\nUrine & serum cross-linked C\xa0telopeptide\nUrine total free deoxypyridinoline\nUrine hydroxyproline\nUrine hydroxylysine glycosides\nSerum tartrate-resistant acid phosphatase\nSerum bone sialoprotein', 'role': 'assistant'}]