What part of the eye controls the amount of light in the eye?

The part of the eye that controls the amount of light entering the eye is the iris. The iris is a colored circular muscle located between the cornea and the lens. It regulates the size of the pupil, which is the opening in the center of the iris. The iris contains muscles that contract or expand in response to the amount of light present in the environment.

In bright conditions, the muscles of the iris contract, causing the pupil to constrict and become smaller. This reduces the amount of light entering the eye, protecting the sensitive structures at the back of the eye from excessive light exposure.

Conversely, in dim conditions, the muscles of the iris relax, causing the pupil to dilate and become larger. This allows more light to enter the eye, improving visibility in low-light environments.

The ability of the iris to adjust the size of the pupil and control the amount of light entering the eye is known as a pupillary reflex. It is an automatic response of the eye to changes in lighting conditions.

Hence, The right option is "Iris".