Final answer:
The pupil is the opening in the iris through which light enters the eye, and its size is adjusted by the iris to control the amount of light reaching the retina.
Step-by-step explanation:
The function of the pupil in the human eye is to act as the opening through which light enters the eye.
The pupil is controlled by the iris, the colored part of the eye, which adjusts the size of the pupil based on the brightness of the light. In bright light conditions, the iris contracts making the pupil smaller to limit the amount of light that enters.
In dim light, the iris relaxes and the pupil enlarges to allow more light to come into the eye. The light that passes through the pupil then goes through the lens, which along with the cornea helps to focus the light on the retina. This process allows us to see clearly at various distances and light conditions.