Opening in the eye through which light passes to the retina is called the?

Step 1: Analyze the question The question asks for the opening in the eye through which light passes to reach the retina. The key word is "opening", meaning a hole or gap, not a tissue or a nerve.

Step 2: Explain the concept (parts of the eye)

• Cornea: the transparent front covering of the eye. It does most of the bending (refraction) of light, but it is a covering, not an opening.
• Iris: the coloured muscular ring. It controls how much light enters by changing the size of the opening, but it is not the opening itself.
• Pupil: the circular opening at the centre of the iris. Light passes through it to the lens and then to the retina.
• Optic nerve: carries electrical signals from the retina to the brain. Light does not pass through it.

Step 3: Work through the options

• A. Pupil: it is the opening in the iris, so it fits.
• B. Cornea: a transparent layer, not an opening. Wrong.
• C. Iris: it surrounds the opening and controls its size. Wrong.
• D. Optic nerve: it transmits signals, not light. Wrong.

Step 4: Answer The correct option is A. pupil.

Tip: Remember that the iris is the "door-keeper" and the pupil is the "door". In bright light the iris makes the pupil smaller, and in dim light it makes the pupil larger. The cornea is like the "window glass" at the front of the eye.