What is an easy way to make a figure prominent with line?

Making its outline darker or thicker

The governing concept is line weight, which means changing the thickness or darkness of a line to control visual emphasis. If the outline of the main figure is made darker or thicker, the eye notices that boundary before weaker surrounding marks, so the figure becomes prominent. This is why option A is correct. Erasing the figure removes information rather than emphasizing it, hiding line direction does not create focus, and turning the paper does not alter the visual hierarchy of the drawing. The artist should still use line weight thoughtfully: a very heavy outline everywhere may flatten the picture, while a stronger outline on the focal figure creates contrast and directs attention. Thus, controlled thickening or darkening is the simple effective method.

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