What should be the next simple exercise after learning primary colours?

Correct answer: Mix two primary colours to make secondary colours

The governing learning sequence in colour theory moves from identifying primary colours to experimenting with their combinations. Mixing two primary paints gives a practical demonstration of secondary-colour formation: red plus yellow produces orange, yellow plus blue produces green, and blue plus red produces violet in the traditional model. The other choices do not practise colour understanding. Therefore option A is the appropriate next exercise.