If brown made from red and green appears too green, what should be increased to balance it?

Correct answer: Red

The governing concept is correction by adjusting the proportions of the colours already forming the mixture. If a brown mixture made from red and green looks too green, increasing red counteracts the excess green and moves the mixture toward a more balanced brown. Therefore option B is correct. Yellow or blue changes the hue in another direction, while white only lightens the value and does not properly correct the green bias.