Which primary colour is generally considered to have the highest light value?

Correct answer: Yellow

The governing concept is colour value, which means the relative lightness or darkness of a colour, not simply its intensity or saturation. In the traditional red-yellow-blue palette, yellow generally has the highest light value and therefore appears lightest. Option C is correct. Blue usually has a lower value, red is intermediate, and magenta is not normally included as a traditional painter’s primary in this model.