The angular momentum of a particle under the influence of a central force is . ? a) Infinite b) Negative c) Zero d) constant

I think the questions is incomplete. 

Generally speaking the angular momentum is a conserved quantity. To get a precise answer, please specify the type of the particle and the physical formalism, since the concept of angular momentum differs in classical mechanics from it in the quantum physics for instance.

it is constant and confined to a plane

is it in the ground state or what? is it in lab or cenre of mass system?

does not change in time, constant