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 vitamin required for hydroxylation of proline \nSelect and explain. \nA. A, B. D, C. C, D. K', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]