The statement, 'Marcus is trying to find a seat in the dark in a movie theater' illustrates the need for the functioning of rods in the retina.
Explanation:
In the visual system, the rods of retina functions for scotopic vision which is vision at low intensities of light; and the cones are responsible for photopic or higher intensities of light.
The rods facilitates vision for light adaptation because they are sensitive to even low levels of intensities of light. Hence, rods help a person to navigate through dark or generally in night vision.
When Marcus is searching for his seat in the darkness of a theater, then his scotopic vision from the rods should function better. The rods can have a larger response even with smaller amount of light because of the action of its photosensitive pigment, rhodopsin which amplifies the light signal.
