B.

This painting uses gradual refinement of texture to make the ground appear to recede into the distance.

Railway tracks converging on the 'vanishing point' is the classic demonstration of linear perspective. But linear perspective is just one of the ways that artists describe 3D space.

Very distant objects (in this case mountains) have much more atmosphere (air, dust and smoke) between them and our eyes, which causes them to look lighter. This effect, in art, is called 'aerial perspective'.

This watercolour painting uses a variation of a formula very popular in the 18th and 19th centuries in Europe: the classical landscape. The dark-ish trees on the left and right frame the distant view and lead our eyes into the picture.

The artist has tried to make this painting work as a painting, without necessarily referring to anything else. Nevertheless, it is almost impossible to look at the shapes and colours without thinking of some as being closer, or further away, than others. Which parts seem to come forward to you? Which seem to pull away?

This painting demonstrates how easily the illusion of space happens in our brains. The three red rectangles seem to sit in front of the cream-coloured 'background', whereas in fact they are almost exactly on the same plane. Perhaps if the rectangles were a different colour, they might look like holes.