In 1935, the Cane Toad Was Introduced to Australia to Control

In 1935, the cane toad was introduced to Australia to control insect pests. Its population has since grown to 2 million, mostly due to ____.

A) herbivory of sugar cane
B) the absence of competing species or natural predators
C) its mutually beneficial relationship with some native species
D) parasitism of sugar cane
E) it only occupies a small niche environment