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': 'What is the value of diurnal variation of IOP above which diagnosis can be made as Glaucoma \nSelect and explain. \nA. 5 mm of Hg, B. 6 mm of Hg, C. 8 mm of Hg, D. 10 mm of Hg', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Difference of IOP of eye between Morning and night\xa0 >8 mm of Hg is diagnostic Glaucoma.', 'role': 'assistant'}]