A bob of mass m attached to an inextensible string of length $l$ is suspended from a vertical support. The bob rotates in a horizontal circle with an angular speed $\omega$ rad/s about the vertical. About the point of suspension :

Question

( A ) angular momentum changes both in direction and magnitude.
( B ) angular momentum is conserved.
( C ) angular momentum changes in direction but not in magnitude.
( D ) angular momentum changes in magnitude but not in direction.