Answer:
The correct answer is "cornea".
Step-by-step explanation:
Often referred as the eye's "window", the cornea is the transparent layer at the front of the eye. In the human eye, most refraction occurs when light passes through the cornea. The refractive power of the cornea, that comes from its clear and curved form, bends the light through the pupil, allowing that most of the light enters to the eye.