Answer:
Option D
Explanation:
The total internal reflection of light takes place. following conditions must be obeyed
(i) The ray must travel from denser to rarer medium.
(ii) Angle of incidence (θ) must be greater than or equal to critical angle (C) i.e,
$C= \sin^{-1}\left(\frac{\mu_{rarer}}{\mu_{denser}}\right)$
Here, $\sin C=\frac{1}{n_{water}}$
and $n_{water}=a+\frac{b}{\lambda^{2}}$
If frequency is less = λ is greater and hence, RI $n_{water}$ is less and therefore, critical angle increases. So, they do not suffer reflection and come out at an angle less than 90°