What happens if tones from different pencil grades are joined without transition?

Correct answer: Hard bands may appear in the shading

The governing concept is a smooth tonal transition between values. Different pencil grades produce different graphite densities, so joining them abruptly can create visible strips or hard bands instead of a gradual change. Option B is correct because the eye reads the sudden value jump as a band. A rounder form, a disappearing cast shadow, or whiter paper does not logically result from an unblended change of pencil grade.