The surface tension of a liquid is 5 N/m. If a film is held on a ring of area 0.02 m², its total surface energy is about: 

• A

  $5\times {10}^{-2}\mathrm{J}$

• B

  $2.5\times {10}^{-2}\mathrm{J}$

• C

  $2\times {10}^{-1}\mathrm{J}$

• D

  $3\times {10}^{-1}\mathrm{J}$