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: Dental
[{'content': 'Flouride poisoning occurs in \nSelect and explain. \nA. Village workers, B. Tooth paste workers, C. Cryolite workers, D. Phosphorus workers', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]