Which combination is best for showing roundness in a cylinder?

Correct answer: Curved lines and gradual value

The correct answer is B: curved lines and gradual value. A cylinder has a curved surface, so lines that follow or describe that curvature help the viewer understand the direction of the surface. Gradual changes in value—from lighter areas to middle and darker areas—show how light turns around the cylinder. Together, these clues create a convincing sense of roundness and three-dimensional form. A is insufficient because a flat rectangle may suggest the side view or a simplified boundary, but it does not show the curved surface by itself. C is insufficient because a bright colour identifies a colour choice, not the turning of a surface. D is a physical fold and does not explain the visual drawing method asked for. The oval ends of a cylinder can also help, but among the given choices B is clearly the best combination. Memory cue: follow the curve with the line and follow the light with value. Do not think that any single colour automatically creates volume.