If a red-violet mixture looks too violet what should be done to make it more red-violet?

Correct answer: Increase red

Red-violet is a mixed hue containing both red and violet. If the mixture appears too violet, the controlled correction is to add a small amount of red, gradually shifting the balance toward red-violet. Therefore option C is correct. Adding blue would push the colour farther toward violet-blue, yellow would alter it in another direction, and green could dull the mixture because it contrasts with red.