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
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: C i.e. Binasal disparity