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
Normal thickness of hybrid layer is: 
Select and explain. 
A. 0.1-5 micron, B. 2-3 micron, C. 0.5-2 micron, D. 5-10 micron
A: 0.1-5 micron
Answer: A: 0.1-5 micron 
Explanation: None