Which of the following choices describes the three varieties of cones?

The correct choice describes the three varieties of cones accurately as being sensitive to the primary colors: blue, red, and green. These cones, known as S-cones (sensitive to short wavelengths, or blue), M-cones (medium wavelengths, or green), and L-cones (long wavelengths, or red), are essential for color vision. The human eye has these photoreceptors to help differentiate a wide range of colors by interpreting the combination and intensity of light that they detect.

The other options do not correctly characterize the cones. Cones are specifically designed for bright light conditions and color perception, not shades of gray, which are instead detected by rod cells. Additionally, cone activity is prominent in well-lit environments, contrasting with what the third choice indicates about their functionality in dim light. Lastly, while peripheral vision primarily relies on rod cells, cones are concentrated in the fovea, the central part of the retina, and are less involved in peripheral vision.