When a sound wave is reflected from a wall, the phase difference between the reflected and incident pressure wave is :

Options

A. frequency of the reflected wave is different to that of incident wave
B. there is a phase difference of `pi//2` is introduced to the reflected wave
C. the reflected wave is out of phase of incident wave and reach the receiving antenna along with the direct wave from transmitting antenna causing interference.
D. the waves are not reflected by the ground.

Answer

C