One of the reasons I initially switched to non-dairy milk was because I learned about the prevalence of lactose intolerance: 65 percent of human population has trouble digesting lactose, the sugar found in milk. For people of East Asian descent like me, up to 90 percent of the population is lactose intolerant.
Red, green and blue are called the primary colors of light. These colors are used to project images in television screens, computer monitors, and anything that transmits light from a light source. But, as artists, we are using pigments (paints, inks, dyes, etc.), not light.
Step one is to define our term. A primary color is a bright color that is useful for mixing other bright colors but cannot itself be made by mixing other colors. Yellow is the perfect example. Try mixing yellow from orange and green, and the result is very dirty, not yellow at all.