Why does changing line direction in cross-hatching increase depth of shade?

Layers of lines increase density and create a darker tone

Cross-hatching creates tone by placing one set of closely spaced lines over another set that runs in a different direction. The second layer fills or visually interrupts some of the white paper between the first lines, increasing the overall mark density. Greater density makes the area appear darker, while wider spacing leaves more paper visible and produces a lighter tone. Changing direction also helps the artist build an even, controlled shade without pressing one line excessively hard. Option A is correct because it identifies the relationship between overlapping layers, density, and tonal value. Option B is false because the paper itself does not change colour, and C and D misunderstand the technique. The governing concept is that the visual amount and spacing of marks control perceived darkness in linear shading.

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