Bt in Bt toxin represents which of the following?

Correct option is D

Insects not only eat plants, bacteria also form an occasional part of their diet, in response several types of bacteria have evolved a defense mechanism against insect predation and one of the example Bacillus thuringiensis is which during sporulation forms intracellular crystalline bodies that contain an insecticidal protein called the endotoxin that accumulates in the bacterium as an inactive precursor, after its ingestion by the insect this protoxin is cleaved by proteases resulting in shorter versions of the protein that display the toxic activity by binding to the inside of the insects mid-gut damaging the surface epithelium creating pores that causes swelling and lysis thus the insect starves to death.