Option D, rarefactions, is the right answer.
The waves in which the displacement of the particles is in the corresponding direction as, or the reverse direction to the way of circulation of the flow is known as the longitudinal waves.
When motion is disclosed from the source, the particles began to reverberate from its rest position and gradual variation in phase vibration is seen at each particle within that swing. The outcome of this comes in the manner that energy transportation takes place from one area to another. These linked actions occur in the flow of alternating regions of rarefaction in the way of transportation of energy.