As a wave travels through a medium, it displaces particles in a direction parallel to the motion of the wave. We can conclude this is a

a transverse wave because the wave is traveling through a medium causing particle displacement.

b longitudinal wave because the wave is traveling in the same direction at all times.

c transverse wave because the particle motion is in the same direction as the way the wave is traveling.

d longitudinal wave because particle displacement is the same direction as the wave.