What problem will occur due to lack of pressure control in line practice?

Correct answer: The darkness and thickness of line will be uncontrolled

Pressure control is the ability to vary and regulate the force applied by a pencil, pen, or other drawing tool. Greater pressure usually produces a darker, wider, or more emphatic mark, while lighter pressure produces a paler and finer mark, although the exact result also depends on the tool and surface. Without control, the artist cannot repeat the intended line quality consistently; some marks may become too dark, thick, abrupt, or weak. Thus option A is correct. Practice with gradual pressure changes helps develop confident contours, varied texture, and tonal transitions. Options B, C, and D do not follow from poor pressure control: it cannot guarantee accuracy, colour paper automatically, or create invisible balance. The governing concept is controlled pressure producing controlled line quality.