A violet mixture appears too red. Which primary colour should be added to balance it?

Correct answer: Blue

The governing concept is balancing the proportions of component pigments. Violet is produced by mixing red and blue. If it looks too red, a small amount of blue increases the blue component and reduces the visible red bias, so option C is correct. Adding more red would intensify the problem; yellow could dull or neutralise the violet, and green is not a primary component in this traditional mixture. Corrections should be gradual.