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': 'The range of level of fluoride secreted by the glands into the mouth is \nSelect and explain. \nA. 0.004-0.005 ppm, B. 0.006-0.007 ppm, C. 0.007-0.05 ppm, D. 0.007-0.08 ppm', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]