How does the main function of the rods differ from that of the cones?

The main function of rods is primarily linked to night vision, which is why the correct choice highlights this aspect. Rods are photoreceptor cells in the retina that are highly sensitive to light and enable vision in low-light conditions. They are particularly effective in detecting motion and shapes in dim environments but do not contribute to color vision or provide detailed visual acuity, which is the role of cones.

In contrast, cones are responsible for color vision and function best under bright light conditions, providing clarity and detail in visual images. Rods are not located in the macula; in fact, the macula is the area of the retina with the highest concentration of cones, which are responsible for high-resolution vision and color detection. This difference in role and location further emphasizes why rods are fundamental for nocturnal or low-light vision rather than for color or detailed imagery.