What correction can be made if the dark colour completely covers the light area during blending?

Correct answer: Lift some colour with a clean brush while the paint is damp

The governing correction principle is controlled lifting of excess pigment before it dries completely. If the painted area is still damp, a clean, slightly damp brush can absorb or lift some dark colour, helping recover part of the lighter passage; the brush should be rinsed and blotted so it does not spread the pigment. Therefore option D is correct. Adding more dark paint or cutting the paper worsens the problem, while painting everything black removes the intended gradation.