What colour is produced on a digital screen by mixing red and green light?

Correct answer: Yellow

This uses additive colour mixing in the RGB system. When red light and green light are emitted together at suitable intensity, the eye perceives their combined stimulation as yellow, making option B correct. Violet would require a blue component with red, blue alone is not the result of red plus green, and black represents the absence of emitted light rather than a mixture of these two active lights.