Final answer:
The pupil is the black-looking opening in the center of the iris that allows light to enter the eye. The iris controls the size of the pupil based on the brightness of the light. It narrows the pupil in bright light and widens it in dim light.
Step-by-step explanation:
The black-looking opening in the center of the iris that allows light to enter the eye is called the pupil.
The size of the pupil is controlled by the iris, which adjusts the size based on the brightness of the light. In bright light, the iris causes the pupil to narrow, and in dim light, it causes the pupil to widen.