A Polluted River Has 20 Homes on It That Rent

A polluted river has 20 homes on it that rent for $1,000 each per month. Homes on a similar river that is not polluted rent for $2,000 each per month. The river is polluted because there are two factories on the river that dump polluted water into it. Each factory could install a filter that would cost $5,000 each and would reduce the pollution in the water to a negligible level. In this case

A) assigning property rights to the river to either party will result in an efficient outcome.
B) if property rights to the river are assigned to the home owners then the factories will be closed.
C) neither party is willing to bargain with the other.
D) if property rights to the river are assigned to the factory then all the homes will be abandoned.