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': 'Normal diurnal variation of intraocular pressure is: \nSelect and explain. \nA. 0-2 mm of Hg, B. 2-3 mm of Hg, C. 3-6 mm of Hg, D. 6-8 mm of Hg', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Ans. 3-6 mm of Hg', 'role': 'assistant'}]