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
[{'content': 'Which of the following elements is not required for hydroxylation of proline in collagen synthesis? \nSelect and explain. \nA. Vit C, B. O2, C. Dioxygenases, D. Pyridoxal phosphate', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Fe2+ and a-ketoglutrate are also needed in hydroxylation of proline for collagen synthesis.', 'role': 'assistant'}]