What is the normal response of pupils to light?

The normal response of pupils to light is that they constrict or become smaller. This physiological reaction is known as the pupillary light reflex and occurs as a protective mechanism to reduce the amount of light entering the eye, thereby helping to prevent damage to the retina and improving visual acuity in bright conditions. When light is shone into one eye, the pupil of that eye and usually the opposite eye (consensual reaction) will constrict simultaneously. This response is controlled by the autonomic nervous system, specifically the parasympathetic division, which increases the constriction of the iris sphincter muscle in response to bright light conditions.

The other options describe either incorrect mechanisms or fail to reflect the expected physiological response to light. The constriction of the pupils in bright light is a fundamental aspect of normal eye function and is critical for maintaining optimal vision and eye health.