Which statement is true for particles of the medium of an earthquake P–wave?
They vibrate in a direction parallel to that of the wave, forming crests and troughs.
They vibrate in a direction parallel to that of the wave, forming compressions and rarefactions.
They vibrate in a direction perpendicular to that of the wave, forming crests and troughs.
They vibrate in a direction perpendicular to that of the wave, forming compressions and rarefactions.