Suppose Two Neighbors Share a Park

Multiple Choice

Suppose two neighbors share a park.One neighbor,Al,leaves trash in the park.This bothers the other neighbor,Bert.According to Coase's Theorem,one necessary condition to alleviate the externality is that

A) Al is fined by the government.
B) Al has the right to leave trash and Bert cannot do anything about it.
C) Bert has the right to a clean park and Al cannot leave trash.
D) Either Al or Bert owns the park.