What effect does the cornea have on the image that enters the eye?

The cornea plays a crucial role in the process of vision by refracting light, which is necessary for focusing images onto the retina. As light enters the eye, it first passes through the cornea, which is curved and transparent. This curvature bends (or refracts) the incoming light rays, directing them toward the lens. The combination of the cornea and the lens optimally focuses the light to create a clear image on the retina, where visual signals are then processed and sent to the brain.

While the cornea does not enhance color perception or determine the brightness of an image, it is essential for ensuring that images are sharp and properly focused. Additionally, it does not act as a filter for harmful rays; that role is primarily taken on by the lens and other parts of the eye. Therefore, the cornea's primary function related to the question is its ability to refract light, making option B the correct choice.