What is formed by adding white to red-orange?

Correct answer: A light red-orange tint

The governing concept is the difference between a tint, shade, and tone. When white is mixed with an existing colour, the result is a lighter version of that same colour, called a tint. Thus, adding white to red-orange produces a light red-orange tint; it does not change the colour into blue, black, or blue-green. Black would create a shade, and grey would generally create a tone. Therefore, option A is correct.