It is a transparent membrane that focuses light that enters eyes to retina.

Correct Answer: A. Lens

The lens is located in the eye. By changing its shape, the lens changes the focal distance of the eye. In other words, it focuses the light rays that pass through it (and onto the retina) in order to create clear images of objects that are positioned at various distances. It also works together with the cornea to refract, or bend, light. The lens consists of the lens capsule, the lens epithelium, and the lens fibers. The lens capsule is the smooth, transparent outermost layer of the lens, while the lens fibers are long, thin, transparent cells that form the bulk of the lens. The lens epithelium lies between these two and is responsible for the stable functioning of the lens. It also creates lens fibers for the lifelong growth of the lens.

• Option B: The sclera is the white part of the eye that surrounds the cornea. In fact, the sclera forms more than 80 percent of the surface area of the eyeball, extending from the cornea all the way to the optic nerve, which exits the back of the eye. Only a small portion of the anterior sclera is visible.
• Option C: The cornea is the eye’s clear, protective outer layer. Along with the sclera (the white of your eye), it serves as a barrier against dirt, germs, and other things that can cause damage. The cornea can also filter out some of the sun’s ultraviolet light. It also plays a key role in vision. As light enters the eye, it gets refracted, or bent, by the cornea’s curved edge. This helps determine how well the eye can focus on objects close-up and far away.
• Option D: Pupils are the black center of the eye. Their function is to let in light and focus it on the retina (the nerve cells at the back of the eye) so one can see. Muscles located in the iris (the colored part of your eye) control each pupil.