c
(c)
As EOTVOS number $E_{\text {s }}$ is dimensionless, we check dimensions of options given to the choose correct answer.
Now, $\left[\frac{\rho g I^2}{\sigma}\right]=\frac{[\rho] \cdot[g] \cdot[L]^2}{[\sigma]}$
$=\frac{\left[ ML ^{-3}\right] \cdot\left[ LT ^{-2}\right] \cdot\left[ I ^2\right]}{\left[ MT ^{-2}\right]}$
$=\left[ M ^{0} L ^{0} T ^0\right]=\text { Dimensionless }$