What type of color scheme can involve tertiary colors?

The triad color scheme is notable for its use of three colors that are equally spaced around the color wheel. This often includes both primary and secondary colors, but it can also incorporate tertiary colors, which are created by mixing primary colors with secondary colors (like yellow-green or blue-purple). Using a triadic color scheme allows for vibrant and dynamic compositions, as the colors tend to maintain a balance while also providing high contrast.

In contrast, monochromatic schemes involve varying shades, tones, and tints of a single color and do not include tertiary colors. Complementary color schemes consist of one color paired with its direct opposite on the color wheel, typically not involving tertiary colors. Analogous color schemes use colors that are next to each other on the color wheel, which again does not typically include the use of tertiary colors. The distinct nature of a triadic color scheme makes it the correct choice for a scheme that can involve tertiary colors.