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': 'Dental fluorosis not associated with skeletal flourosis are seen at: \nSelect and explain. \nA. 1 ppm fluoride, B. 3 ppm fluoride, C. 8 ppm fluoride, D. 10 ppm fluoride', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]