A square current-carrying loop is placed in a uniform magnetic field B with the plane of the loop parallel to the magnetic field. (See drawing). The dashed line is the axis of rotation. The magnetic field exerts:

a) a net torque, but not a net force, on the loop

b) a net force and a net torque on the loop

c) a net force, but not a net torque, on the loop

d) neither a net force nor a net torque on the loop