If the shadow on a cylinder is like a flat band and not gradual, what is the error?

Correct answer: Value gradation of the curved surface is missing

Direct answer: A, missing value gradation on the curved surface. A cylinder turns gradually from the light-facing side to the side turned away from the light. Therefore its light and dark values should normally change smoothly across the curved surface, unless a special, sharply focused lighting effect is intentionally being shown. A hard, flat band makes the cylinder look like a cut-out or a flat-sided object because the transition does not describe the turning surface. Option B is wrong because hue means the colour family, such as red or blue; the problem concerns lightness and darkness, called value. Option C is wrong because suitable paper cannot replace correct observation and shading. Option D is wrong because a cylinder is a regular geometric form, not an organic form. First identify the light source, then place the highlight, middle values, core shadow, and reflected light carefully. Memory cue: curved surfaces need gradual value change.