An artist needs a warm brown. Which colour should be added in a small amount to a neutral red and green mixture?

Correct answer: Red or orange

The governing concept is colour temperature: warm hues such as red and orange push a neutral brown toward a warmer, reddish or golden appearance. A small addition is important because the mixture should be adjusted gradually and not overwhelmed. Option A is therefore correct. Blue would cool the brown, while extra green or violet would not reliably create the requested warm direction and could make the mixture duller.