What is the net force experienced by a bar magnet placed in a uniform magnetic field?
The forces of magnitude mB act opposite to each other and hence, net force acting on the bar magnet due to external uniform magnetic field is zero. So, there is no translational motion of the magnet.
However, the forces are along different lines of action and constitute a couple. Hence, the magnet will rotate and experience torque.
If the magnetic field was non-uniform, then both force and torque would act.
The correct option is A.