Which of the following is not considered a primary color?

The question focuses on the concept of primary colors, which are fundamental in color theory and are used to create other colors. In the traditional color wheel used in art and design, primary colors typically refer to red, blue, and yellow. These colors cannot be created by mixing other colors together; instead, they serve as the base from which other colors can be mixed.

Green, in contrast, is classified as a secondary color. It is formed by mixing the primary colors blue and yellow. Therefore, it is not considered a primary color within the context of this question. Understanding this classification system is essential for artists and designers, as it influences how they mix colors to achieve the desired outcomes in their work.