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 best age of starting fluoride supplementation 
Select and explain. 
A. Birth, B. 1 month, C. 2 year, D. 3 years
A: Birth
Answer: A: Birth 
Explanation: Dietary Fluoride Supplementation Schedule