What is the most likely result of adding too much black to blue-green?

Correct answer: The colour will become excessively dark and lifeless

Black lowers the value of a colour, so adding too much of it makes blue-green much darker. Excess black also suppresses the visual liveliness and clarity of the original hue, causing the result to appear dull or lifeless. It does not increase saturation, transform the mixture into yellow-green, or convert a tertiary colour into primary blue. A controlled amount may create a shade, but excessive black produces the undesirable result described in option D.