Which one of the following is not a primary color?

Primary colors are defined as the foundation of all other colors and cannot be created by mixing other colors together. In traditional color theory, particularly the RYB (Red, Yellow, Blue) model commonly used in art and design, the primary colors are red, blue, and yellow.

Green, on the other hand, is considered a secondary color because it is made by mixing two of the primary colors: blue and yellow. Therefore, identifying green as not being a primary color aligns accurately with the fundamental principles of color theory.

Understanding primary and secondary colors is crucial for anyone in the field of hair coloring, as it helps in creating desired shades and tones by mixing colors effectively. Recognizing which colors serve as the building blocks of all other hues allows haircolorists to make informed choices when formulating hair color.