The Major Factor in the Population Explosion of the Zebra

The major factor in the population explosion of the zebra mussel in the Great Lakes region is ____.​

A) ​the zebra mussel's specialist ecological niche
B) ​because it has a hard shell that protects it from predation
C) ​its ability to latch onto to boats and travel to new locations
D) ​the illegal importation for restaurant food
E) ​its rapid reproductive rate and its lack of natural enemies that might control its population