Explanation

(c) Let $I_{r}and\ I_{i}$ represent the intensities of reflected and incident waves respectively, then
$\frac{I_{r}}{I_{i}} = \left( \frac{\mu - 1}{\mu + 1} \right)^{2}$
$Where\ \mu = \frac{v_{1}}{v_{2}}$
$Or\ \ \ \ v = \frac{\sqrt{\frac{T}{m_{1}}}}{\sqrt{\frac{T}{m_{2}}}} = \sqrt{\frac{m_{2}}{m_{1}}} = \sqrt{\frac{25}{9}} = \frac{5}{3}$
$\therefore\frac{I_{r}}{I_{i}} = \left\lbrack \frac{\left( \frac{5}{3} \right) - 1}{\left( \frac{5}{3} \right) + 1} \right\rbrack^{2} = \frac{1}{16}$