Question

what label should replace letter b? close together = compression wavelength compression amplitude rarefaction

Explanation:

In a longitudinal wave (like a sound wave), compression is where particles are close together, and rarefaction is where particles are spread out. The label \( b \) in the diagram (assuming it's over the spread - out region) should be rarefaction. The options are wavelength (distance between two identical points), compression (close together), amplitude (maximum displacement), and rarefaction (spread out). Since the diagram shows a region opposite to compression (close together), rarefaction is the correct label.

Answer:

rarefaction