If cream becomes too yellow what should be added to make it lighter and more balanced?

Correct answer: White

The governing concept is adjustment of a light tint by changing its value and saturation. Adding white to an overly yellow cream mixture increases lightness and dilutes the visual strength of the yellow, making the result paler and more balanced. Option D is correct for the intended school-level paint-mixing situation. Red would make the mixture warmer, black would darken it, and blue could neutralise yellow but might shift the cream toward a dull greenish or grey appearance rather than simply producing a lighter cream. White should be added in small stages.