Where Did the Pesticide Bt Originally Come from and What

Where did the pesticide Bt originally come from and what does it do?

A) It's from a bacteria species and it kills insects.
B) It's from a caterpillar that eats other insects.
C) It's from corn and cotton plants and kills caterpillars.
D) It's a genetically engineered toxin designed by scientists to kill caterpillars.
E) It's from a bacteria species and it kills corn and cotton plants.