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
[{'content': 'Critical angle of air corneal interface - \nSelect and explain. \nA. 36 degree, B. 46 degree, C. 56 degree, D. 66 degree', 'role': 'user'}, {'content': 'Answer: B \nExplanation: 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', 'role': 'assistant'}]