Making the same line light to dark shows which skill?

Pressure control

The governing concept is pressure control in drawing. A pencil deposits more or less graphite according to the force applied by the hand: gentle pressure produces a light mark, while increased pressure produces a darker and often wider-looking mark. Gradually moving from light to dark therefore demonstrates that the artist can vary hand pressure smoothly and intentionally, making option A correct. Changing the paper does not itself create a controlled tonal transition. Removing colour is unrelated to a graphite line, and hiding the picture does not describe any drawing skill. Good pressure control is useful for outlines, shading, texture, and corrections because it lets the artist create hierarchy without changing tools. The transition should be gradual rather than an accidental jump, showing control of both force and movement.

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