A point charge$+2\mu C$  is placed at the centre of a sphere of radius 10cm. Another charge $-2\mu C$ is kept at a distance of 20 cm from the centre of the sphere. Then electric flux through the surface of the sphere is

• A

  $3.26\times {10}^{16}\mathrm{V}\text{-}\mathrm{m}$

• B

  $2.26\times {10}^{17}\mathrm{V}\text{-}\mathrm{m}$

• C

  $4.18\times {10}^{18}\mathrm{V}\text{-}\mathrm{m}$

• D

  $5.12\times {10}^{15}\mathrm{V}\text{-}\mathrm{m}$