A square loop of side $2a$ and carrying current I is kept in $xz$ plane with its centre at origin. A long wire carrying the same current I is placed parallel to $z-$axis and passing through point $(0, b , 0),( b >> a ) .$ The magnitude of torque on the loop about $z-$ax is will be
  • A$\frac{2 \mu_{0} I^{2} a^{2} b}{\pi\left(a^{2}+b^{2}\right)}$
  • B$\frac{\mu_{0} I^{2} a^{2} b}{2 \pi\left(a^{2}+b^{2}\right)}$
  • C$\frac{\mu_{0} I^{2} a^{2}}{2 \pi b}$
  • D$\frac{2 \mu_{0} I^{2} a^{2}}{\pi b}$
JEE MAIN 2020, Diffcult
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