Cones come in how many types and what wavelengths do they correspond to?

• A. Two types corresponding to red and green wavelengths
• B. One type sensitive to all wavelengths
• C. Three types corresponding to short, medium, and long wavelengths and they work best in bright light
• D. Four types corresponding to ultraviolet, blue, green, and red wavelengths

Answer: (C)

There are three cone types in the human eye, each tuned to a different portion of the spectrum: short-wavelength (blue), medium-wavelength (green), and long-wavelength (red). The brain interprets color by comparing the activity levels across these three channels, which lets us distinguish a wide range of hues. These cones require bright light to function well, so color vision is most accurate in daylight or well-lit conditions (photopic vision). In dim light, rods take over and color perception fades toward grayscale. The other options aren’t correct because humans don’t have just two cone types, there isn’t a single cone sensitive to all wavelengths, and there isn’t a fourth cone type for ultraviolet in humans.