Twinkling of stars is due to atmospheric
(a) dispersion of light by water droplets
(b) refraction of light by different layers of varying refractive indices.
(c) scattering of light by dust particles
(d) internal reflection of light by clouds.
Explanation : When sun light enters the earth’s atmosphere, it continuously goes from rarer to the denser medium and hence refraction of light
takes place. The refraction of light taking place in the atmosphere is known as atmospheric refraction.