Two opposite and equal charges each of magnitude $4 \times 10^{-8} \text{ C}$ form a dipole. Their separation is $2 \times 10^{-2} \text{ cm}$. When this dipole is placed in an external electric field of $4 \times 10^8 \text{ NC}^{-1}$,the value of maximum torque and the work done in rotating it through $180^{\circ}$ respectively will be:

• A
  $64 \times 10^{-4} \text{ Nm}$ and $64 \times 10^{-4} \text{ J}$
• B
  $32 \times 10^{-4} \text{ Nm}$ and $32 \times 10^{-4} \text{ J}$
• C
  $64 \times 10^{-4} \text{ Nm}$ and $32 \times 10^{-4} \text{ J}$
• D
  $32 \times 10^{-4} \text{ Nm}$ and $64 \times 10^{-4} \text{ J}$