Night Vision: Dilated Pupil and Relaxed Lens for Distant Low-Light Viewing

Steps:

• In darkness, the pupil dilates to maximize light entry into the eye.
• Viewing distant objects like the night sky requires the lens to relax into a thinner shape for far focus.
• Diagrams must show a large pupil and thin lens to match these conditions.
• Compare choices: identify pairs with dilated pupil and relaxed lens.

Why D is correct:

• Option D pairs diagrams 2 and 4, both depicting dilated pupils and thin lenses, aligning with the pupillary light reflex (constriction in bright light, dilation in dim) and accommodation for infinity focus.

Why the others are wrong:

• A (1 and 3): Includes constricted pupils, incorrect for low light.
• B (1 and 4): Includes constricted pupil in diagram 1, unsuitable for night.
• C (2 and 3): Includes thick lens in diagram 3, wrong for distant viewing.

Final answer: D