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 caries reduction benefits of water fluoridation to  primary teeth and permanent teeth  respectively - \nSelect and explain. \nA. 10-30%, 30-50%, B. 40-50%, 50-60%,, C. 10-20%, 20-40%, D. 50-70%, 60-80%', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Murray\xa0 reviewed\xa0 113\xa0 studies\xa0 conducted\xa0 in\xa0 23\xa0 countries to help clarify various reports on the benefits to primary teeth of communal water fluoridation.72\xa0 A thorough review of the data clearly showed that water fluoridation provides protection for primary teeth against dental caries but to a somewhat lesser degree for permanent teeth. The\xa0 caries\xa0 reduction\xa0 benefits\xa0 to\xa0 primary\xa0 teeth\xa0 ranged\xa0 between 40% and 50%, whereas the range for permanent teeth was between 50% and 60%.', 'role': 'assistant'}]