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
[{'content': 'Grades of binocular vision- \nSelect and explain. \nA. Grade 1: Fusion, B. Grade 2: Fusion, C. Grade 1: Stereopsis, D. Grade 2: Stereopsis', 'role': 'user'}, {'content': 'Answer: B \nExplanation: 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', 'role': 'assistant'}]