What is the primary function of rods in the human eye?

The primary function of rods in the human eye is to provide vision in dim light conditions. Rods are photoreceptor cells located in the retina that are highly sensitive to light, making them essential for night vision and seeing in low-light settings. Unlike cones, which are responsible for color vision and function best in bright light, rods do not detect color and have a lower spatial acuity. However, their ability to respond to very low light levels allows us to perceive shapes and movement in darkness. This capability is vital for survival, as it enables us to navigate and react to our environment when lighting conditions are poor.

The other options relate to different aspects of vision and the overall functioning of the eye but do not accurately describe the specific role of rods. Cones, for instance, are responsible for color visualization, while the transmission of visual impulses to the brain is a broader function that involves the entire visual pathway, including ganglion cells and the optic nerve. The process of bending light rays pertains to the eye's lens and cornea, which aids in focusing light, rather than the specific function of rods.