What part of the eye is primarily responsible for night vision?

The rods are primarily responsible for night vision due to their high sensitivity to light. They are photoreceptor cells located in the retina that can detect low levels of light, making them essential for seeing in dimly lit environments. Rods do not perceive color, which is why vision in low light is primarily monochromatic, but they can detect motion and provide peripheral vision effectively.

In contrast, cones are responsible for color vision and function best in bright light conditions. The pupil and lens play supporting roles by regulating the amount of light entering the eye and focusing images on the retina, but they are not directly responsible for the process of night vision itself. Therefore, the correct answer highlights the specific role of rods in allowing humans to see in low-light conditions.