Which combination of colored lights does not produce a secondary color?

The correct combination that does not produce a secondary color is yellow and blue. In color theory, particularly in additive color mixing, primary colors (red, green, and blue) combine to form secondary colors.

When two primary colors are mixed, they create secondary colors: red and green produce yellow, red and blue create magenta, and green and blue yield cyan. However, yellow is not a primary color in the additive mixing model; it is a secondary color formed by red and green light. Therefore, mixing yellow (a secondary color) with blue (a primary color) does not yield another secondary color but often results in a mixture that leans towards green.

In contrast, the other combinations do involve mixing primary colors, which consistently leads to the formation of secondary colors.