Four identical thin rods each of mass M and length l form a square frame. Moment of inertia of this frame about an axis through the centre of the square and perpendicular to its plane is :

• A

  $\frac{1}{3}{\mathrm{Ml}}^2$

• B

  $\frac{4}{3}{\mathrm{Ml}}^2$

• C

  $\frac{2}{3}{\mathrm{Ml}}^2$

• D

  $\frac{13}{3}{\mathrm{Ml}}^2$