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
When using a supplemental fluoride for the systemic water fluoridation, which is the most important factor to be taken into consideration: 
Select and explain. 
A. Mean climatic temperature, B. Number of topical fluoride treatments to be given, C. Amount of supplemental fluoride given by the physician and the dentist, D. Mean age of the child
A: Mean climatic temperature
Answer: A: Mean climatic temperature 
Explanation: None