All three visible faces of a cube are painted with soft gradations making its planar structure weak. What is a better method?

Correct answer: Fill each face with a distinct nearly even value and keep edges clear

A cube is an angular form made of distinct planar faces, so its structure is communicated through separate values and clear boundaries rather than continuous rounded shading. Give each visible face a different, nearly even value according to the light direction and keep the edges readable. Therefore, option D is correct. One value removes plane contrast, erased edges weaken structure, and circular strokes suggest a rounded form instead of a cube.