If the potential of a capacitor having capacity 6 $\mathrm{\mu }$F is increased from t0 volt to 20 volt, thon increase in energy will be

• A

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

• B

  $9\times {10}^{-6}\mathrm{J}$

• C

  $9\times {10}^{-4}\mathrm{J}$

• D

  $4\times {10}^{-6}\mathrm{J}$