When a mechanical sinusoidal wave propagates through a medium. 

Particles of the medium must oscillate in a direction perpendicular to the direction of propagation of wave.

Only disturbance propagates through the medium with a definite velocity which depends upon the elastic and inertia property of the medium.

Particles of the medium may oscillate about their mean positions parallel to the direction of propagation.

Both (2) and (3) are correct.