Which test best reveals whether a blue pigment is biased toward green or toward violet?

Correct answer: Mixing it separately with yellow and red pigments and observing the results.

The governing concept is colour bias, meaning a pigment’s slight tendency toward a neighbouring hue. Mix the blue separately with a clean yellow and a clean red, keeping quantities and conditions similar. A green-leaning blue generally makes cleaner greens with yellow, while a violet-leaning blue behaves differently in mixtures with red. Thus A is the practical test; the other actions do not reveal hue bias reliably.