Respuesta :
Answer: The correct answer is rarefaction.
Explanation:
Sound wave is a longitudinal wave. It consists of the compression and rarefaction.
Compression: It is the region in the sound wave where the density of the air molecules are more. Here, the air pressure is high.
Rarefaction: It is the region in the sound wave where the density of the air molecules are least. Here, the air pressure is low.
Frequencies: The number of complete oscillations per second.
Pitches: It is the characteristic of the sound wave. It depends on the frequency.
Therefore, the correct answer is rarefaction.
