Lamprey Populations Introduced into the Great Lakes Have Grown Dramatically

Lamprey populations introduced into the Great Lakes have grown dramatically. Why?

A) Fishers have intentionally introduced them with the hope of farming them for "eel skin."
B) Lamprey stocking programs have been highly effective.
C) A fish species that they naturally prey upon has recently been introduced into the Great Lakes.
D) Competitive species have driven them from the ocean.
E) They have no natural predators in these waters.