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
[{'content': 'The critical angel of cornea-air interface is \nSelect and explain. \nA. 36deg, B. 46deg, C. 56deg, D. 66deg', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. b. 46deg', 'role': 'assistant'}]