Iris

A) Photoreceptor cells that function in black and white vision
B) Photoreceptor cells that function in color vision
C) The opening in the iris
D) The innermost tunic of the eye
E) A pigmented contractile structure

Iris

The colored part of the eye surrounding the pupil, responsible for controlling the size of the pupil and thus the amount of light that enters the eye.

Photoreceptor Cells

Specialized neurons in the retina that convert light into electrical signals, enabling vision.