Which of the following is not a primary color?

In the context of color theory, particularly in relation to the traditional primary colors of art, red, blue, and yellow are universally recognized as primary colors. These colors cannot be created by mixing other colors together; instead, they serve as the foundational building blocks for creating all other hues.

Green, on the other hand, is a secondary color that results from the mixing of two primary colors, specifically blue and yellow. This characteristic of green as a secondary color makes it distinct from the primary colors, which are integral to color mixing in both painting and other visual art forms. Understanding the relationships between primary, secondary, and tertiary colors is fundamental for artists and designers in achieving desired color palettes and contrasts in their work.