If yellow is continuously increased in an orange mixture which direction will the colour move toward?

Correct answer: Yellow-orange

The governing concept is proportional influence in a colour mixture. Orange lies between red and yellow, so increasing the yellow component gradually shifts the mixture toward the yellow side of the colour wheel. The expected direction is yellow-orange, making option D correct. Red-violet and green are not the immediate target directions, and brown would usually result from dulling or combining less-related pigments rather than simply increasing yellow in orange.