4 Companies located at different points on a river dump many quantities of effluent into it. The effluent adversely affects quality of swimming for homeowners who live downstream. These people can build swimming pools to avoid swimming in the river, and firms can purchase filters that eliminate harmful chemicals in the material that is dumped into the river.

As a policy advisor for a regional planning organization, how would you compare and contrast the following options for dealing with the harmful effect of the effluent:

a.) An equal rate effluent fee on firms located on the river.
b.) An equal standard per firm on the level of effluent each firm can dump.
c.) A transferable effluent permit system in which the aggregate level of effluent is fixed and all firms receive identical permits.