Of All of the Freshwater Organisms,more Freshwater Clams Are Becoming

Of all of the freshwater organisms,more freshwater clams are becoming endangered than other species.What is the likely reason?

A) They are a primitive animal and they are due for natural extinction
B) The shellfish industry has moved inland and we are overharvesting them for human food
C) Clams are more heavily parasitized than any other molluscan group
D) As filter-feeders,they concentrate pollutants and are more likely to be harmed by water pollution
E) All of the choices are correct