A short bar magnet having magnetic moment `M=0.80 JT^1` is placed in uniform magnetic field of 0.30 T. If bar magnet is free to rotate in plane of field, then (where U is potential energy and tau is torque)

Options

A. at stable equilibrium, `U=0.24 J`, `tau=0`
B. at State equilibrium `U=0.24` J, `tau != 0`
C. at stable equilibrium `U=-0.24` J, `tau=0`
D. at unstable equilibrium `U=-0.24` J, `tau=0`