Pupillary Reflex Receptors Detect Light in the Eye

Steps:

• The pupillary reflex adjusts pupil size in response to light changes.
• Light enters the eye and stimulates sensory receptors.
• These receptors convert light into neural signals for the brain.
• The reflex pathway starts at the retina, leading to pupil constriction.

Why D is correct:

• The retina contains photoreceptors (rods and cones) that detect light intensity, initiating the pupillary light reflex as defined in ocular physiology.

Why the others are wrong:

• A. The brain processes signals but does not contain the initial light-detecting receptors.
• B. The iris controls pupil size via muscles but lacks sensory receptors for light.
• C. The pupil is an opening for light entry, not a site for receptors.

Final answer: D