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: Pathology
Marker of bone formation are all except ? 
Select and explain. 
A. Osteocalcin, B. Alkaline phosphatase, C. Procollagen residue, D. Hydroxyproline
D: Hydroxyproline
Answer: D: Hydroxyproline 
Explanation: Ans. is 'd' i.e., HydroxyprolineHydroxyproline is a marker of bone resorption ( not bone formation).