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
Grades of binocular vision- 
Select and explain. 
A. Grade 1: Fusion, B. Grade 2: Fusion, C. Grade 1: Stereopsis, D. Grade 2: Stereopsis
B: Grade 2: Fusion
Answer: B: Grade 2: Fusion 
Explanation: Woh described three grades of binocular single vision - Grade I - Simultaneous perception. It is the power to see two dissimilar objects simultaneously. Grade II - Fusion. It consists of the power to superimpose teo incomplete but similar images to form one complete image. Grade III - Stereopsis. It consists of the ability to perceive the third dimension(depth perception). Ref; A.K.Khurana; 6 th Edition; Page no: 342