Why Are Contaminants Such as TCEs and PCBs So Difficult

Why are contaminants such as TCEs and PCBs so difficult to remove using traditional methods?

A) They are so volatile they escape into the atmosphere so they're impossible to contain.
B) They naturally degrade into harmless forms that cannot be distinguished from the natural chemical makeup of the environment.
C) They are too toxic to be safely handled.
D) They easily adsorb onto organic matter in the environment.