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
The caries reduction benefits of water fluoridation to  primary teeth and permanent teeth  respectively - 
Select and explain. 
A. 10-30%, 30-50%, B. 40-50%, 50-60%,, C. 10-20%, 20-40%, D. 50-70%, 60-80%
B: 40-50%, 50-60%,
Answer: B: 40-50%, 50-60%, 
Explanation: Murray  reviewed  113  studies  conducted  in  23  countries to help clarify various reports on the benefits to primary teeth of communal water fluoridation.72  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  caries  reduction  benefits  to  primary  teeth  ranged  between 40% and 50%, whereas the range for permanent teeth was between 50% and 60%.