Is Huygens' principle valid for longitudinal sound waves?

$A$ point source of light is placed at the focus of a concave mirror. Consider only paraxial rays. The shapes of the wavefronts of incident and reflected lights respectively are

The idea of secondary wavelets for the propagation of a wave was first given by

What is the shape of the wavefront on Earth for sunlight?

Explain the refraction of a plane wave from a denser to a rarer medium using Huygens' principle.

Given below are two statements:
Statement-$I$: $A$ plane wave after passing through a prism remains a plane wave, but passing through a small pinhole may become a spherical wave.
Statement-$II$: The curvature of a spherical wave emerging from a slit will increase for increasing slit width.
In the light of the above statements, choose the correct answer from the options given below.