Which type of wave is characterized by the compression and rarefaction of air molecules?

The type of wave characterized by the compression and rarefaction of air molecules is a sound wave. Sound waves are longitudinal waves, where air molecules move parallel to the direction of the wave's travel. As the sound wave propagates, it causes regions of high pressure (compressions) and low pressure (rarefactions) in the medium through which it travels, typically air. These variations in pressure are what allow the sound to be transmitted from one location to another.

In contrast, light waves are electromagnetic waves that do not require a medium to travel through; they can propagate through the vacuum of space. Water waves exhibit a different behavior as they typically involve both longitudinal and transverse motion, resulting in surface movement rather than air molecule compression. Electromagnetic waves also differ from sound waves by not involving any interactions with air molecules, since they consist of oscillating electric and magnetic fields. Thus, the characteristics of sound waves distinctly highlight their nature, making it clear why sound waves are the correct answer to this question.