Correct answer (c ) refraction of rays of sun passing through the atmosphere.
The setting sun often looks oval in shape because of refraction of rays of sun passing through the atmosphere
This is due to the refraction of light coming
from the sun. When light comes from the sun it generally travel from rarer
medium to denser medium i.e., it travels from space to the atmosphere.
Early sunrise:- it is due to that when the sun is below the
horizon at that time the light from the sun enters to atmosphere from space at
get refracted away from the normal line of sun and it causes early sunrise.
Delayed sunset:- it is due to the reason that when the sun goes below the
horizon at that time the sun light passes from space to atmosphere and it again
get refracted from the normal line of the sun and it causes the delayed sunset.