This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Optics and refraction, Subject name: Ophthalmology
Centre of biconvex lens is called - 
Select and explain. 
A. Focal point, B. Optical center, C. Epicentre, D. Focal Distance
B: Optical center
Answer: B: Optical center 
Explanation: optical center is the point in the principal axis of a lens through which light passes without undergoing any detion. It is in the center of lens. Reference : AK khurana 7th edition