question: What part of the eye allows light to enter?
distractor3: iris
distractor1: eyelid
distractor2: retina
correct_answer: pupil
support: Take-Home Experiment: The Pupil Look at the central transparent area of someone’s eye, the pupil, in normal room light. Estimate the diameter of the pupil. Now turn off the lights and darken the room. After a few minutes turn on the lights and promptly estimate the diameter of the pupil. What happens to the pupil as the eye adjusts to the room light? Explain your observations. The eye can detect an impressive amount of detail, considering how small the image is on the retina. To get some idea of how small the image can be, consider the following example.