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 & tissue sealants act by 
Select and explain. 
A. Killing micro-organism causing caries, B. Blocking nutrient supply to bacteria, C. Neutralising acid produced by bacteria, D. All of these
B: Blocking nutrient supply to bacteria
Answer: B: Blocking nutrient supply to bacteria 
Explanation: None