Which is the most suitable way to show the volume of an object through line?

Drawing contour lines that follow the surface curve

Volume means the appearance of three-dimensional mass, and lines can suggest it by responding to the surface of the object. Contour lines that follow a form’s curvature wrap around its surface in the viewer’s imagination. On a rounded object, curved contours can indicate bulging; on a cylindrical object, they can show the change in surface direction. Option A is therefore the most suitable method because the lines describe the form rather than merely enclosing it. Option B may flatten the object if all marks ignore its curvature. Options C and D provide too little information about the surface, so they cannot effectively communicate volume. The governing concept is that line direction and curvature should correspond to the observed three-dimensional form. Such lines are especially useful when shading is limited or when structure must be shown clearly.

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