Final answer:
Rods are the part of the eye that detect black and white and shades of gray, particularly sensitive to low light and important for peripheral and night vision. Cones, in contrast, enable color vision.
Step-by-step explanation:
The part(s) of the eye that can only detect black and white and shades of gray is/are called rods. Rods are photoreceptors in the retina that respond in low light conditions and are responsible for vision in very dark environments. Unlike rods, cones are the photoreceptors that respond in intense light and are responsible for color vision. There are approximately 120 million rods in the human retina, and these rods do not yield color information but allow us to discern grey scales under low light conditions.