The correct option is C Bacillus thuringiensis toxin
Bacillus thuringiensis (Bt) is a bacteria and used as an active ingredient in some insecticides. Bacillus thuringiensis (Bt) is an insecticide with unusual properties that make it useful for pest control in certain situations. Several strains can infect and kill insects. Because of this property, Bt has been developed for insect control. At present, Bt is the only microbial insecticide in widespread use.