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
Bone resorption markers are - 
Select and explain. 
A. Serum propeptide of type I procollagen, B. Osteocalcin, C. Urine total free deoxypyridinoline, D. Free glutamic acid cross linkage
C: Urine total free deoxypyridinoline
Answer: C: Urine total free deoxypyridinoline 
Explanation: Markers of bone resorption

Urine & serum cross-linked N telopeptide
Urine & serum cross-linked C telopeptide
Urine total free deoxypyridinoline
Urine hydroxyproline
Urine hydroxylysine glycosides
Serum tartrate-resistant acid phosphatase
Serum bone sialoprotein