Why are multiple pencil grades used in deep shading?

Correct answer: To gain better control from light to dark values

The governing concept is value control through graphite hardness. Harder grades make lighter, cleaner marks, while softer grades deposit more graphite and produce deeper darks. Using several grades therefore gives better control across the full range from light to dark, making option A correct. Pencil grades cannot change paper size or add colour, and they do not remove a cast shadow; they only help render its value accurately.