Which of the following is not considered a primary color?

The correct answer is orange, as it is not classified as a primary color in the traditional color theory. Primary colors are the fundamental colors that cannot be created by mixing other colors; in the context of subtractive color mixing, which applies to pigments and paints, these primary colors are red, blue, and yellow.

Orange is a secondary color, resulting from the mixing of red and yellow. In contrast, red and blue are indeed primary colors within this framework. Green also qualifies as a secondary color, being the product of mixing blue and yellow. This classification is crucial in understanding color mixing and the foundational concepts in design and art. Knowing which colors are primary helps when creating new colors through mixing and can influence various applications in floristry and artistic endeavors.