Which statement correctly distinguishes a form from a shape?

• A. A form can never appear three-dimensional.
• B. A shape has volume in all cases.
• C. A form is two-dimensional in all contexts.
• D. A form appears to be three-dimensional.

Answer: (D)

The core idea here is the difference between depth and flat boundaries. Shapes are flat, two-dimensional boundaries—think of a circle or square drawn on a page. Forms carry depth and volume, either as real three-dimensional objects or as depicted with shading and perspective that imply three dimensions. Because of that depth cue, a form can look three-dimensional.

So the best statement is that a form appears to be three-dimensional, since it emphasizes the perception of depth and volume that distinguishes forms from flat shapes. The other options misstate the nature of depth and volume for forms and shapes.