Answer:
Longitudinal
Step-by-step explanation:
Sound wave is a type of mechanical wave which required medium to transmit the energy from one point to other point.
here in longitudinal waves the medium molecules will oscillates or move to and from about their mean position parallel to the wave propagation.
While in transverse waves the medium particles will oscillates in perpendicular direction to the propagation of waves.
So here sound wave is described by its property of propagation through the medium and due to this way of propagation we say it as Longitudinal waves.