How can line show light and shadow difference on the same object?

By drawing closely spaced, denser lines in shadow areas and widely spaced, sparse lines in light areas

Line drawing can represent value, or the relative lightness and darkness of an area, through hatching and related techniques. When marks are placed close together, overlap, or become darker and more numerous, the eye reads that region as having greater tone and therefore as darker. Wider spacing, fewer marks, or lighter pressure leaves more of the paper visible and suggests light. Consequently, option A correctly assigns dense lines to shadow and sparse lines to light. Option B would flatten the value difference, option C reverses the tonal logic, and option D supplies only a contour rather than modelling the surface. The effect should be adjusted gradually so that the object still appears unified and the light direction remains believable.

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