Which photoreceptors are essential for color discrimination?

• A. Rods
• B. Ganglion cells
• C. Amacrine cells
• D. Cones

Answer: (D)

Color discrimination relies on photoreceptors that can distinguish different wavelengths of light. That role is fulfilled by cones in the retina. Cones come in multiple types, each tuned to different parts of the spectrum (roughly short, medium, and long wavelengths). The brain interprets color by comparing the responses of these different cone types, which allows us to perceive a wide range of colors, especially in bright light when cones are active and provide high-acuity vision.

Rods, while highly sensitive in low light and good for grayscale, do not convey color information, so they don’t support color discrimination. Other retinal neurons like ganglion and amacrine cells are important for processing and transmitting visual signals, but they aren’t the photoreceptors that determine color.