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
Pit and fissure sealant used in primary prevention of caries is 
Select and explain. 
A. BIS - GMA, B. Duraphat, C. Fluor protector, D. APF gel
A: BIS - GMA
Answer: A: BIS - GMA 
Explanation: None