Answer: Pressure fluctuations travel along the direction of propagation of the sound wave.
Step-by-step explanation:
Sound wave is a type of longitudinal wave. It is defined as a wave which consist of vibrations of particles traveling through a medium( such as air, or water).
Sound wave is propagated by the alternating adiabatic compression and expansion of the medium. The COMPRESSIONS are regions of high air pressure while the RAREFACTIONS are regions of low air pressure. Therefore, Since a sound wave consists of a repeating pattern of high-pressure and low-pressure regions moving through a medium, it is sometimes referred to as a PRESSURE WAVE.
The direction of the vibrating particles is parallel to the direction of propagation and that's why it's a type of LONGITUDINAL WAVE. Therefore, the correct option that
concludes about the direction in which such pressure fluctuations travel is
(Pressure fluctuations travel along the direction of propagation of the sound wave.)