Use the Figure to the Right to Answer the Next

Multiple Choice

Use the figure to the right to answer the next problem.
A ball of mass of mass m is tied with a light string to a vertical post of radius R_p and slides on a frictionless horizontal surface. As the ball travels around the post, the string wraps around the post, shortening the length. At t = 0 s, its speed is v_o and radius is r_o.
-What is the angular momentum of the ball after the string has wrapped once around the post?

A)
B)
C)
D)
E) cannot be determined