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': 'Daily vitamin A intake \nSelect and explain. \nA. 1000 I.U, B. 2000 I.U, C. 3000 I.U, D. 4000 I.U', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]