Which of the following are primary colors?

The primary colors in traditional color theory, particularly in painting and art, are yellow, red, and blue. These colors are considered primary because they cannot be created by mixing other colors together; instead, they serve as the foundation for creating a wide range of other colors through mixing. For example, mixing yellow and red produces orange, red and blue produce purple, and blue and yellow yield green.

The other options consist of colors that are either secondary or neutral. Green, purple, and orange are secondary colors formed by mixing primary colors. Black, white, and grey are often referred to as neutral colors or shades, which do not fit into the primary or secondary categories. Cyan, magenta, and yellow are indeed primary colors in the subtractive color model used in color printing, but the context of the question likely refers to the traditional primary colors. Thus, yellow, red, and blue represent the primary colors from the standpoint of conventional color mixing.