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: Biochemistry
Which of the following elements is not required for hydroxylation of proline in collagen synthesis? 
Select and explain. 
A. Vit C, B. O2, C. Dioxygenases, D. Pyridoxal phosphate
D: Pyridoxal phosphate
Answer: D: Pyridoxal phosphate 
Explanation: Fe2+ and a-ketoglutrate are also needed in hydroxylation of proline for collagen synthesis.