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': 'The function of vitamin A is/are related to which of the following? \nSelect and explain. \nA. Retinol, B. Retinal, C. Retinoic acids, D. All of the above', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]