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': 'Tonography helps you to determine: \nSelect and explain. \nA. The rate of formation of aqueous, B. The facility of outflow of aqueous, C. The levels of intraocular pressure at different times., D. None of the above', 'role': 'user'}, {'content': "Answer: B \nExplanation: Tonography is a noninvasive technique for determining the facility of aqueous outflow. Ref: Parson's Diseases of The Eye, 18th Edition, Page 7226", 'role': 'assistant'}]