Magnetic Effects of Current and Magnetism: JEE Main 2020 Physics question

A square loop of side 2$a$, 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 the z-axis and passing through the point (0, b, 0), (b >> a). The magnitude of the torque on the loop about zaxis is given by :