What is the likely result if too much blue is added to red-orange?

Correct answer: A muted brown or grey mixture

The governing concept is complementary neutralisation in subtractive mixing. Blue is opposite the red-orange family on the colour wheel, so combining them reduces chromatic intensity; when blue is added excessively, the mixture commonly becomes dull brown, grey, or otherwise muddy depending on the pigments. Option C is correct. More blue cannot make red-orange brighter, it does not produce pure yellow, and pink requires a light red or white rather than excessive blue.