What can applying several light layers in pencil shading be called?

Correct answer: Layering

The governing concept is controlled tonal buildup. In pencil shading, the artist applies one light layer of graphite and then adds further light layers until the desired value is reached. This gradual process is called layering or layer building, so option D is correct. Erasing removes graphite, cutting changes the paper, and colour mixing combines pigments rather than building a graphite value through repeated strokes.