Which color schemes are based on three colors?

The correct answer identifies triads as a color scheme that is explicitly based on three colors. Triadic color schemes utilize three colors that are evenly spaced on the color wheel, creating a vibrant and balanced color palette. This method often leads to striking visual contrast while maintaining harmony, as the colors support and complement one another well.

Analogous color schemes, while incorporating three or more colors, typically consist of colors that are adjacent to each other on the color wheel. Although they can sometimes involve three colors, the essence of this scheme lies in the closeness of colors rather than a fixed triadic relationship.

Split-complementary is a variation of the complementary color scheme. It involves one base color and two colors adjacent to its complementary color. While this scheme can also involve three colors, it is less straightforwardly classified as a 'three-color scheme' because of the relationship between the colors.

In summary, triad specifically refers to three colors that create a structured triadic color scheme, making it the principal focus of the answer.