The Poisonous Cane Toad Was Introduced to Australia to Control

The poisonous cane toad was introduced to Australia to control cane beetles.It had no effect on the beetles, but in the absence of predators, it has been consuming many other native species.This is an example of

A) successful introduction of an exotic species.
B) controlling a species by removing its resources.
C) a source population becoming a sink population.
D) successful use of biological control of a non-native species.
E) an intended biological control organism becoming a pest, itself.