Which mixture can create a muted red without changing its value too much?

Correct answer: Add a very small amount of green

The governing concept is complementary colour neutralisation. Green is opposite red on the colour wheel, so a very small amount can reduce red’s intensity and make it muted. Because the quantity is small, the value changes less than it would with a large amount of white or black. Thus B is correct. White makes a tint, black makes a shade, and extra yellow shifts the hue toward orange rather than simply muting it.