A then spherical shell A of radius R is concentrically placed inside another then spherical shell B of radius 2R. Electric flux through the surface of shell A is +2 volt-m and that through the surface of B is +8 volt-m. The electric charge enclosed bt the region bounded by the shells A and B is

• A

  $48.5\times {10}^{-6} \mathrm{coul}$

• B

  $36.2\times {10}^{-10} \mathrm{coul}$

• C

  $12.6\times {10}^{-8} \mathrm{coul}$

• D

  $53.1\times {10}^{-12} \mathrm{coul}$