The adjustable opening in the center of the eye through which light enters?

The adjustable opening in the center of the eye through which light enters?

• A. Cornea
• B. Lens
• C. Aqueous humor
• D. Pupil

Answer: (D)

The adjustable opening is the pupil, the central hole in the iris that controls how much light enters the eye. When it’s bright, the iris contracts the sphincter muscles to make the pupil smaller, protecting the retina by reducing light. In dim light, the dilator muscles relax to enlarge the pupil, letting in more light for better visibility. The cornea and lens are responsible for bending and focusing light, not serving as the opening, and the aqueous humor is the fluid in the front of the eye, not an opening.

The adjustable opening is the pupil, the central hole in the iris that controls how much light enters the eye. When it’s bright, the iris contracts the sphincter muscles to make the pupil smaller, protecting the retina by reducing light. In dim light, the dilator muscles relax to enlarge the pupil, letting in more light for better visibility. The cornea and lens are responsible for bending and focusing light, not serving as the opening, and the aqueous humor is the fluid in the front of the eye, not an opening.