How does line help us understand form?

It shows boundary, curve, and direction of an object

The governing concept is form described through contour and structural lines. Form refers to the visual character and three-dimensional presence of an object, while lines help the viewer understand how its surface begins, ends, bends, or changes direction. An outer contour shows the boundary, and selected internal or structural lines can indicate curves, folds, edges, and orientation. Therefore option A is correct because boundary, curve, and direction together provide visual evidence about the object’s form. Making an object invisible is the opposite of drawing it, and sound or smell cannot be communicated directly by an ordinary visual line. Lines do not create every detail alone, but they give the viewer a framework for interpreting volume, shape, and construction.

This is a Class 9 Art Education question. Chapter: Elements of Art. Topic: Form.