The Best Way to Block Asian Carp from Moving into the Great

The best way to block Asian carp from moving into the Great Lakes from the Illinois River would be the closing of locks and dams in and near Chicago; however, these waterways are not being closed because

A) Republicans in the U.S. Congress are concerned about taxes on the rich.
B) as major transportation links for the region, they are important for the economy of St. Louis.
C) too many Asian carp are already clogging the locks and dams and cannot be removed.
D) as major transportation links for the region, they are important for Chicago's economy.
E) the economies of neighboring states depend on the Chicago-area locks and dams.