Which colour is formed when more blue is used in a mixture of blue and yellow?

Correct answer: Blue-green

The governing concept is proportional colour mixing. Blue and yellow together produce green, but when blue is used in greater quantity, the mixture shifts toward the blue side of the green range and becomes blue-green. Thus B is correct. More yellow would move the result toward yellow-green, while red-violet and yellow-orange require different colour combinations and are not produced by simply increasing blue in blue-yellow paint.