Question

which part of the wave is labelled with the letter b? image of a wave with labels a and b options: compression, crest, rarefaction, trough

Explanation:

The diagram shows a longitudinal wave (like a sound wave). In longitudinal waves, rarefaction is the region where particles are spread out, between compressions (where particles are close). The label B is between the compressed regions (A is a compression), so B is rarefaction.

Answer:

C. Rarefaction