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 is required for the conversion of 25-hydroxy-cholecalciferol to calcitriol? \nSelect and explain. \nA. 25-hydroxylase, B. 1-hydroxylase, C. UV light, D. 1,25-hydroxylase', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]