Yellow is considered to be one of the primary colours, but there is no cone specialized to respond to yellow light. When we see yellow it is because the light is stimulating:
A) the S cones very little and the L and M cones equally
B) the S cones very little, the L cones greatly, and the M cones moderately
C) the S and M cones equally and the L cones very little
D) the S and L cones equally and the M cones greatly

Question

Quizplus · Accepted Answer

Yellow light stimulates the L (long-wavelength) and M (medium-wavelength) cones equally, while the S (short-wavelength) cones are stimulated very little. This combination is perceived as yellow by the human brain.

Yellow Is Considered to Be One of the Primary Colours