Which type of waves can propagate in solids?

Sound waves exhibit more diffraction than light waves because:

Mechanical waves on the surface of a liquid are

Among the following statements,the correct statement for a wave is

$Assertion :$ When a beetle moves along the sand within a few tens of centimeters of a sand scorpion,the scorpion immediately turns towards the beetle and dashes towards it.
$Reason :$ When a beetle disturbs the sand,it sends pulses along the sand's surface. One set of pulses is longitudinal while the other set is transverse.

The figure shows wave fronts in still water moving in the direction of the arrow towards the interface $PQ$ between a shallow region and a deep (denser) region. Which of the lines shown may represent one of the wave fronts in the deep region?