A soap bubble (surface tension $\left.30\times {10}^{-3}\mathrm{N}/\mathrm{m}\right)$  has radius 2 cm. The work done in doubling the radius is

• A

  zero

• B

  $1\cdot 1355\times {10}^{-4}\mathrm{J}$

• C

  $2\cdot 261\times {10}^{-4}\mathrm{J}$

• D

  $9.04\times {10}^{-4}\mathrm{J}$