The iris is a colored muscle that adjusts the size of the

A) blind spot.
B) cornea.
C) pupil.
D) lens.

The iris is responsible for controlling the size of the pupil, which is the opening through which light enters the eye. The size of the pupil regulates the amount of light that enters the eye and reaches the retina. The iris is made up of muscles that contract or relax depending on the amount of light entering the eye. Therefore, the iris does not affect the cornea, lens or blind spot.