This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Miscellaneous, Subject name: Ophthalmology
Critical angle of air corneal interface - 
Select and explain. 
A. 36 degree, B. 46 degree, C. 56 degree, D. 66 degree
B: 46 degree
Answer: B: 46 degree 
Explanation: Criticalangle for the cornea-air interface is approximately 46 degrees. Total internal reflection prevents direct visualization of ang le in nearly all eyes. Ref khurana 6/e