4. what is the function of the iris? a it converts light into electrical signals that are sent to the brain through the optic nerve. b it contracts and expands to control the amount of light that enters the eye. c its curved surface to focus light entering the eye. d it focuses the light onto the light-sensor cells at the back of the eye.

B It contracts and expands to control the amount of light that enters the eye.

Explanation:

The iris is the circular and thin structure of the eye. It is responsible for regulating the size of the pupil. This when expands and contracts controls the amount of light entering the eye's retina.

When the bright light enters the eye the iris closed the pupil so that less light enters the eye. But when the light is low, the iris open the pupil to allow more light to enter the eye and focuses the light rays onto the retina.

i think its 5049.

i hope this !

im doing test rn im going with 2 but ill give answer if itss wrong,   : )