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: Social & Preventive Medicine
[{'content': 'RDA of Retinol during pregnancy \nSelect and explain. \nA. 500 mcg, B. 600 mcg, C. 700 mcg, D. 800 mcg', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]