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
Hydroxylation of proline require the following except: 
Select and explain. 
A. Fe+2, B. O2, C. Ascorbic acid, D. Succinate
D: Succinate
Answer: D: Succinate 
Explanation: None