If equal amounts of blue and orange produce a very muddy colour, what is the most appropriate next step?

Correct answer: Make a fresh mixture in small amounts on a clean palette

The governing concept is controlled colour mixing. Blue and orange are complementary colours, so equal quantities can strongly neutralise each other and create a dull, muddy result. Starting again with small measured amounts on a clean palette gives better control over hue and proportion. Adding every colour, much white, or much black will not restore the original colour and may make the mixture less controllable. Therefore, option A is correct.