Which one of the following phenomena is not explained by Huygen's construction of wavefront?

Which of the following is correct for light diverging from a point source?

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.

What does Huygens' principle explain regarding secondary wavelets?

On a hot summer night,the refractive index of air is smallest near the ground and increases with height from the ground. When a light beam is directed horizontally,the Huygens' principle leads us to conclude that as it travels,the light beam

$A$ parallel beam of light strikes a piece of transparent glass having a cross-section as shown in the figure below. The correct shape of the emergent wavefront will be (figures are schematic and not drawn to scale)-