Bt toxin (from Bacillus thuringiensis) is produced as an inactive protoxin (Cry protein). When insect larvae ingest it, the alkaline pH and proteases in the gut convert it into the active toxin, which then binds to midgut epithelial cells causing pore formation and insect death.

Now evaluating options:

Incorrect → Bt produces protoxin, not active toxin

Incorrect → toxin targets midgut cells, not ovaries

Incorrect → Bacillus does not produce antitoxins

Correct → activation occurs in insect gut

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