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
Recommended dosage of fluoride mouth rinse for 12-14 year old is 
Select and explain. 
A. 10 ml 0.2% NaF twice daily, B. 10 ml 0.2% NaF once daily, C. 10 ml 0.2% NaF twice monthly, D. 10 ml 0.2% NaF once monthly
C: 10 ml 0.2% NaF twice monthly
Answer: C: 10 ml 0.2% NaF twice monthly 
Explanation: None