If orange becomes too red what can be added to balance it?

Correct answer: Yellow

The governing concept is correcting a mixture by changing the proportion of its component colours. Orange is produced from red and yellow; if it looks too red, adding a little yellow increases the yellow proportion and shifts the mixture back toward balanced orange. Therefore, option C is correct. Blue, violet, or black would make the colour duller, darker, or move it toward a different hue rather than simply correcting the red bias.