A point mass `m` is attached to a massless string whose other end is fixed at `P` as shown in figure. The mass is undergoing circular motion in `xy`-plane with centre `O` and constant angular speed `Omega`. If the angular momentum of the system, calculated about `O and P` be `L_O and L_P` respectively, then
Options:
(a) `L_O and L_P` do not vary with time
(b) `L_O` varies with time while `L_P` remains constant
(c) `L_O` remains constant while `L_P` varies with time
(d) `L_O and L_P` both vary with time