When is line used like a main guiding element in a scene?

When it leads the viewer's eye to the main subject

The governing concept is the leading line, a compositional line that guides the viewer’s eye through the image toward an important subject or focal area. A road, fence, riverbank, branch, or repeated edge may create such a path. When its direction supports the composition, the viewer’s attention moves from an entry point toward the main subject, so option A is correct. A leading line does not hide every subject; instead, it organises visual movement and can create emphasis or depth. Cutting paper is a craft action rather than a compositional function, and a directionless picture is the opposite of what a leading line achieves. The line need not be an actual drawn stroke: it may be implied by aligned objects, repeated marks, or edges that visually point toward the focus.

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