Here's why:

* Pigments and Light Absorption: Pigments, like xanthophylls, absorb certain wavelengths of light and reflect others. The color we see is the reflected light.

* Xanthophylls and Absorption: Xanthophylls primarily absorb blue and violet light, which are at the shorter wavelength end of the visible spectrum.

* Yellow Reflection: Because they absorb blue and violet, xanthophylls reflect the remaining wavelengths, primarily green and yellow, resulting in their characteristic yellow color.

This is the same principle that applies to other pigments like chlorophyll (reflects green), carotenoids (reflects orange), and anthocyanins (reflects red).