A uniform rod $O A$ of mass $M$ and length $2 \pi$ rests on a smooth table and is free to turn about a smooth pivot at its end $O$, in contact with it at a distance $b$ from $O$ is an inelastic particle of mass $m$, a horizontal blow of impulse $p$ is given to rod at a distance $x$ from $O$ in a direction perpendicular to the rod. The resultant instantaneous angular velocity of the rod is:
(a) $\frac{p x}{\frac{4 M a^{2}}{3}+m b^{2}}$
(b) $\frac{p x}{M}$
(c) $\frac{p x}{m a^{2}+m b^{2}}$
(d) none of these