If orange mixed from red and yellow appears too red, what is the most suitable correction?

Correct answer: Add a little yellow

The governing concept is colour mixing: orange is produced by combining red and yellow. If the mixture looks too red, its balance has shifted toward the red component. Adding a small amount of yellow moves the mixture back toward a balanced orange. More red would worsen the error, while blue or black would change or dull the hue rather than correct its red bias.