This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Ocular motility and squint, Subject name: Ophthalmology
True stereopsis is perceived due to the following - 
Select and explain. 
A. Overlay of contours, B. Motion parallax, C. Bi- nasal disparity, D. Linear perspective
C: Bi- nasal disparity
Answer: C: Bi- nasal disparity 
Explanation: Stereopsis is a term that is most often used to refer to the perception of depth and 3-dimensional structure obtained on the basis of visual information deriving from two eyes by individuals with normally developed binocular vision. It is used for binasal disparity Ref khurana 6/e p456