Question

the arrow is pointing to what part of the wave? the arrow is pointing to what part of the wave? compresson rarefaction trough crest

Explanation:

In a wave, compression is the region where particles are close together. Rarefaction is where particles are spread apart. Trough is the lowest point in a transverse wave (not relevant here as it's a longitudinal wave shown). Crest is the highest point in a transverse wave (also not relevant here). The arrow points to a region where particles are close - together, which is compression.

Answer:

compression