Metamer concept: which statement is correct?

• A. They can look the same under certain lighting even with different spectral distributions.
• B. They always look different under all lighting.
• C. They require UV light to be perceived.
• D. They refer to materials that never change color under light.

Answer: (A)

Metamerism happens when two colors have different spectral power distributions but produce the same perceptual color under a given light and observer. Because the eye combines the incoming light into color signals, those two different spectra can map to identical color sensations under that illuminant, so they look the same even though their spectra differ. This is why the statement is correct: they can appear identical under certain lighting despite having different spectral distributions. If the lighting changes, those spectra can no longer produce the same perception, so metamers may look different under other illuminants. The other options don’t fit because metamers don’t require UV light to be perceived, they aren’t colors that never change with light, and they are specifically about different spectra that happen to look the same under some lighting, not about always looking different.