An insulating rod of length $ \ell$ carries a charge $q$ uniformly distributed on it. The rod is pivoted at its centre and is rotated with a frequency $F$ about a fixed axis perpendicular to the rod and passing through the pivot. The magnetic moment of the rod system is

Question

$\begin {array} {1 1} (a)\;Zero & \quad (b)\; \pi qF\ell^2 \\ (c)\;\pi qF\ell^2/3 & \quad (d)\;\pi qF\ell^2/6 \end {array}$