Long Beach Island, Off the Coast of New Jersey, Is

Long Beach Island, off the coast of New Jersey, is considering building a sand barrier to protect the houses on the island from future hurricanes. The marginal social benefit of the barrier is equal to the

A) marginal private benefit of the person who benefits the most from the barrier.
B) marginal private benefit of the person who benefits the least from the barrier.
C) sum of the marginal private benefits for anyone who benefits from the barrier.
D) difference between the marginal private benefit of the person who benefits the most and the person who benefits the least from the barrier.