Which mixture can create blue-violet?

Correct answer: More blue added to violet

The governing concept is tertiary-colour formation on the colour wheel. Violet is produced from red and blue; when a little more blue is added, the mixture shifts toward the blue side and becomes blue-violet. Thus option C is correct. Adding green to yellow gives a yellow-green direction, yellow with red moves toward orange, and red added to orange produces red-orange rather than blue-violet.