A paper disc of radius R from which a hole of radius r is cut out, is floating in a liquid of surface tension T. The force on the disc due to surface tension will be

• A

  $\mathrm{\pi RT}$

• B

  $2\pi (R+r)T$

• C

  $\mathrm{\pi }(\mathrm{R}+\mathrm{r})\mathrm{T}$

• D

  $4\mathrm{\pi }(\mathrm{R}+\mathrm{r})\mathrm{T}$