What is a simple way to make brown with poster colours?

Correct answer: Mix red, yellow, and a little blue

The governing concept is subtractive colour mixing with pigments. First, red and yellow can be mixed to form orange; adding a small amount of blue, its complementary partner, neutralises the orange toward brown. The blue should be added gradually because too much can make the mixture dark or dull. Option A is correct, while white alone lightens and blue-white produces a tint rather than brown.