What is the correct process for forming a secondary colour?

Correct answer: Mixing two primary colours

The governing concept is the traditional pigment colour system. A secondary colour is produced by mixing two primary pigments in suitable proportions: red with yellow gives orange, yellow with blue gives green, and blue with red gives violet. White only changes lightness, black and white make a neutral grey, and layering one colour does not create a new colour family. Therefore option A is correct.