What happens when a dark poster colour is applied over a light colour?

Correct answer: The dark colour can cover the light colour

The governing concept is the opacity of poster colour. A sufficiently thick dark layer reflects and blocks much of the light, so it can hide or cover a lighter layer beneath it, especially after the first layer has dried. This is why artists often paint broad dark shapes over lighter areas during layering. Option A is correct. The other choices describe effects that do not follow from applying a darker opaque paint layer.