How may yellow poster colour appear if too much black is added?

Correct answer: Olive or muddy

Adding black lowers the value and brightness of yellow. With too much black, the mixture can lose its clear yellow appearance and look dark, olive, or muddy, making option B correct. Black does not change yellow directly into pure blue or bright pink. Light orange would usually be approached by combining yellow with a suitable amount of red or orange, not by adding black. The exact appearance also depends on the pigments and their proportions.