Which of the following color is not considered as primary color in the visible light spectrum?

In the visible light spectrum, the primary colors are Red, Green, and Blue (RGB color model). Pink is not considered a primary color because it is not a pure spectral color - pink is actually a desaturated or lighter form of red, created when white light is added to red. Pink exists in our perception but not as a distinct wavelength in the electromagnetic spectrum. Orange and Yellow, while secondary in some color models, are actual spectral colors.