Which question is most useful for distinguishing form from shape?

Correct answer: Does it have depth and volume?

The correct answer is D: does it have depth and volume? A shape is generally two-dimensional, having height and width but appearing flat. A form is three-dimensional, so it has height, width, depth and volume. A drawing of a circle is a flat shape, while shading can make it appear like the form of a sphere. Asking about depth and volume therefore checks the essential difference directly. A is wrong because warm colour concerns colour, not dimensionality. B is about the construction or appearance of a line and does not tell us whether an object is flat or solid. C concerns texture, which describes how a surface feels or appears, but a flat drawing can also suggest texture. D is the strongest diagnostic question because depth and volume are the key clues to form. Memory cue: shape is flat; form occupies space. Remember that a shape can be used to represent a form, but the two terms are not identical.