$A$ square loop of side $2a$ carrying current $I$ is kept in the $XZ$ plane with its centre at the origin. $A$ long wire carrying the same current $I$ is placed parallel to the $z$-axis and passes through the point $(0, b, 0)$,where $b >> a$. The magnitude of the torque on the loop about the $z$-axis is given by:

• A
  $\frac{2 \mu_{0} I^{2} a^{2}}{\pi b}$
• B
  $\frac{\mu_{0} I^{2} a^{3}}{2 \pi b^{2}}$
• C
  $\frac{\mu_{0} I^{2} a^{2}}{2 \pi b}$
• D
  $\frac{2 \mu_{0} I^{2} a^{3}}{\pi b^{2}}$