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
Current recommendation for systemic flouride supplements for all children residing in areas where the water flouride deficient until they reach the age 
Select and explain. 
A. 12, B. 14, C. 16, D. 18
A: 12
Answer: A: 12 
Explanation: None