Correct option is (c) frequency does not change
As, the light enters from rarer medium to the denser medium, the speed of light decreases but the frequency remains the same. The relation between speed of light, wavelength and the frequency is given as v = nλ
where, v is the speed of light, n is the frequency of light and λ is the wavelength of light.
\(\therefore\) n = v/λ
In denser medium, n remains constant and v decreases. Therefore, 2 also decreases to keep the frequency constant.
