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
To prevent sensitivity caused by acid etching and to protect pulp in deep cavities which of the following should be used. 
Select and explain. 
A. Ca(OH)2 liner, B. ZOE, C. Light cured GIC liner, D. Varnish
A: Ca(OH)2 liner
Answer: A: Ca(OH)2 liner 
Explanation: None