Which colour is formed when a little more red is added to orange?

Correct answer: Red-orange

The governing concept is the effect of colour proportion in a mixture. Orange already lies between red and yellow, and adding a little more red shifts the hue toward the red side. The resulting named tertiary colour is red-orange, so option A is correct. Yellow-green, blue-green, and blue-violet contain green or blue components and cannot describe a mixture of orange with additional red. The direction of the added colour determines the new hue.