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': 'Daily dose of Fe for adult man \nSelect and explain. \nA. 34 mg/d, B. 24 mg/d, C. 18 mg/d, D. 40 mg/d', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]