When is the use of a wavy line suitable for visual flow?

Correct answer: When water, air, flowing cloth, or gentle movement is to be shown

Direct answer: B, when water, air, flowing cloth, or another gentle movement needs to be shown. A wavy line is made from repeated soft rises and falls. Because the eye follows these curves smoothly, the line suggests flow, rhythm, flexibility, and movement. To choose a suitable line, first identify the character of the subject. If the subject bends, flows, ripples, or moves gently, a wavy line can communicate that quality. A is less suitable because a hard wall usually needs straighter, firmer structural lines. B is correct because the listed examples have fluid or flexible movement. C is wrong because complete stillness and rigidity are more naturally suggested by stable straight or controlled lines. D is wrong because technical measurement generally requires precise geometric marks rather than expressive waves. A wavy line is not limited to water; it may also suggest hair, smoke, a breeze, or moving fabric when the context supports it. Memory cue: wavy lines wander and flow; straight lines usually build and stabilize.