When red is added to blue-violet in which direction will the hue generally shift?

Correct answer: Toward red-violet

Hue shift is understood by observing which component is increased and then locating the movement on the colour wheel. Blue-violet already contains blue and violet; adding red strengthens the red side of the mixture, moving it toward red-violet. Hence option B is correct. The other directions move toward green or yellow and do not follow the added red component.