Which of the following is classified as a primary color?

A primary color is a color that cannot be created by mixing other colors together. In the traditional color mixing model, which is often used in art and design, the primary colors are red, blue, and yellow. Blue is one of these primary colors, making it foundational for creating a wide range of other colors through mixing.

For example, when combined with yellow, blue can create green, and when mixed with red, it produces purple. This quality of being able to mix with other colors to create new hues is what underscores blue's role as a primary color.

The other options—green, orange, and purple—are all secondary or tertiary colors formed by mixing primary colors. Orange is created by mixing red and yellow, green by mixing blue and yellow, and purple by blending blue and red. Understanding primary colors is crucial in color theory, as they form the basis for creating all other colors in the color wheel.