A ring of mass m, radius R having charge q uniformly distributed over it and free to rotate about its own axis is placed in a region having a magnetic field B parallel to its axis. If the magnetic field is suddenly switched off, the angular velocity acquired by the ring is

Question

$\begin {array} {1 1} (a)\;\large\frac{qB}{m} & \quad (b)\;\large\frac{2qB}{m} \\ (c)\;\large\frac{qB}{2m} & \quad (d)\;Zero \end {array}$