A spherical liquid drop is placed on a horizontal plane. A small disturbance causes the volume of the drop to oscillate. The time period of oscillation $\left(T\right)$ of the liquid drop depends on the radius $\left(r\right)$ of the drop, density $\left(\rho \right)$ and surface tension $\left(S\right)$ of the liquid. Which among the following will be a possible expression for the time period? where $k$ is a dimensionless constant.

• A

  $k\sqrt{\frac{\rho r}{S}}$
• B

  $k\sqrt{\frac{{\rho }^{2}r}{S}}$
• Correct answer
  C

  $k\sqrt{\frac{\rho r^3}{S}}$
• D

  $k\sqrt{\frac{\rho r^3}{S^2}}$

Hence, the correct answer is option: 'C'.