How are secondary colours formed?

Correct answer: By mixing two primary colours

The governing concept in traditional colour theory is colour mixing. A secondary colour is produced by combining two primary colours in suitable proportions: red and yellow make orange, yellow and blue make green, and blue and red make violet or purple. Therefore option A is correct. Mixing black and white produces grey, while water changes the consistency or lightness of paint rather than creating a secondary hue; repeating one colour creates no new colour.