When is it better to add a dark colour gradually into white rather than adding white into a dark colour?

Correct answer: When a very light and controlled tint is needed

The governing concept is controlled tinting. White is usually used as the light base, while a small quantity of a dark colour can change the value quickly. Adding the dark colour gradually to white lets the artist observe each change and stop at the desired light tint, so option A is correct. Adding white to a dark colour is less efficient when only a pale, controlled tint is required.