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
Tonography helps you to determine: 
Select and explain. 
A. 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
B: The facility of outflow of aqueous
Answer: B: The facility of outflow of aqueous 
Explanation: Tonography is a noninvasive technique for determining the facility of aqueous outflow. Ref: Parson's Diseases of The Eye, 18th Edition, Page 7226