This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Conjunctiva, Subject name: Ophthalmology
[{'content': 'The normal pH of tear is \nSelect and explain. \nA. 5.7, B. 7.5, C. 6.5, D. 7.9', 'role': 'user'}, {'content': 'Answer: B \nExplanation: pH of tear is 7.4 Refe: Khurana 6th edition page number 366', 'role': 'assistant'}]