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
5% NaF in resinous base is: 
Select and explain. 
A. Duraphat., B. Cavity shield., C. Duraflour., D. Carex
B: Cavity shield.
Answer: B: Cavity shield. 
Explanation: None