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': '"Maidon Teeth" is due to: \nSelect and explain. \nA. Lead, B. Fluoride, C. Calcium, D. Phosphorus', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Fluoride', 'role': 'assistant'}]