Concept: This question tests your basic knowledge of the anatomy of the human eye, specifically identifying the central opening within the iris.

Why (B) is correct: The iris is the colored part of the eye that controls the size of the pupil. The pupil is the central, adjustable opening in the iris through which light enters the eye. Its size changes to regulate the amount of light reaching the retina.

Why other options are wrong:

• (A) Cornea: The cornea is the transparent outer layer at the front of the eye that covers the iris, pupil, and anterior chamber.
• (C) Lens: The lens is a transparent, biconvex structure behind the iris that focuses light onto the retina.
• (D) Fovea centralis: The fovea centralis is a small, central pit in the retina responsible for sharp, detailed central vision.

Common Mistake: Students sometimes confuse the iris (the colored structure) with the pupil (the opening within it).

NEET Tip: Remember that the pupil is like the aperture of a camera, controlling light entry, and the iris is the diaphragm that adjusts it.

Correct Answer: (B)