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: Ophthalmology
The critical angel of cornea-air interface is 
Select and explain. 
A. 36deg, B. 46deg, C. 56deg, D. 66deg
B: 46deg
Answer: B: 46deg 
Explanation: Ans. b. 46deg