Question

what part of the eye controls the amount of light entering through the pupil?
sclera
lens
cornea
iris

Explanation:

The iris is a muscular structure in the eye. It can change its shape to adjust the size of the pupil. When there is more light, the iris makes the pupil smaller to reduce the amount of light entering. When there is less light, it makes the pupil larger to allow more light in. The sclera is the tough outer layer of the eye, the lens focuses light, and the cornea is the clear front - part that helps refract light. None of these (sclera, lens, cornea) control the light - entering amount through the pupil like the iris does.

Answer:

Iris