Which colour can be added to mute a bright orange slightly?

Correct answer: Blue

The governing concept is complementary colour mixing. Blue lies opposite orange on the colour wheel, so a very small amount of blue reduces orange’s brightness and moves it toward a muted neutral. Option C is correct. Yellow or red would usually make the orange warmer or stronger, while white would lighten it and create a tint rather than specifically neutralising its intensity. Add blue gradually because too much can make the mixture dull or brownish.