A cube of side b has a charge q at each of its vertices. The electric field due to this charge distribution at the centre of this cube will be

• A

  $\mathrm{q}/{\mathrm{b}}^2$

• B

  $\mathrm{q}/2{\mathrm{b}}^2$

• C

  $32\mathrm{q}/{\mathrm{b}}^2$

• D

  Zero