Poster colour

The governing concept is even drying in poster-colour painting. A thick layer contains more moisture, so strong sunlight may dry the upper surface faster than the lower part. This unequal shrinkage creates internal stress and can produce cracks or lifting. Therefore option A is correct. The other options describe unlikely results: sunlight does not normally make the paint more flexible, strengthen the paper, or automatically level a thick layer. Dry the work gradually in normal air.

The governing colour-theory concept is complementary neutralisation. Yellow and violet are complementary colours, so mixing a small quantity of yellow into violet can reduce its intensity. However, adding too much of the complement pushes the mixture toward a dull neutral grey or brown. Option A is therefore correct. The lightness of the yellow, the dryness of the violet, and a clean palette do not by themselves explain excessive greying; the controlling error is quantity.

The governing practical concept is controlling paper expansion during wet painting. Water makes paper fibres swell, and uneven wetting and drying can leave the sheet buckled even when the colour layer is smooth. Option A is most effective because suitable heavier paper, secured on all sides to a rigid board, is supported while it dries. More water increases swelling, folding creates creases, and direct sunlight can cause uneven drying and surface stress.

The governing concept is even coverage in a flat poster-colour fill. When excess wet paint flows toward a boundary and remains there, the thicker edge dries with more pigment and appears as a dark band. Therefore, option A is correct. A suitable brush, a clean palette, and an even working pace usually support uniform coverage; they do not themselves cause pigment to accumulate at the edges.