A conical pendulum consists of a simple pendulum moving in a horizontal circle as shown. C is the pivot . O is the circle in which the pendulum moves.and $w_1$ the angular velocity of the bob. If L is the angular momentum about C, then

Question

a) $ \bar {L}$ is constant

b) only direction of $\bar {L} $ is constant

c) only magnitude of $\bar {L}$ is constant

d) none of the above