Answer:
Magnetic field must be in YZ plane except in negative and positive Z direction.
Explanation:
Here loop is in XY plane and current direction as defined then its magnetic moment is in negative Z direction.
Now we know torque on a loop is calculated by
Torque=magnetic moment × B (vector cross product)(Here B is magnetic field)
Thus magnetic field can be in the positive and negative Y direction and Z direction.
diagram is in attachment.