Which part of the eye is primarily responsible for regulating the amount of light that enters the pupil?

• A. Iris
• B. Cornea
• C. Retina
• D. Lens

Answer: (A)

Verified step by step guidance

1. Understand the function of each part of the eye listed in the options: Iris, Cornea, Retina, and Lens.
2. Recall that the Iris is the colored part of the eye surrounding the pupil and controls the size of the pupil.
3. Recognize that by adjusting the pupil size, the Iris regulates how much light enters the eye.
4. Note that the Cornea helps focus light, the Retina processes visual information, and the Lens adjusts focus, but none regulate light entry.
5. Conclude that the Iris is primarily responsible for regulating the amount of light entering the pupil.