What is the most accurate basis for identifying a secondary colour in the traditional pigment system?

Correct answer: It is formed by mixing two primary colours

In the traditional pigment colour wheel, the governing rule is that a secondary colour results from combining two primary pigments. Red and yellow produce orange, yellow and blue produce green, and blue and red produce violet, subject to the pigment system used. Therefore option A is correct. White alone changes value, darkness is not a defining feature, and option D contradicts the process of colour mixing.