The correct option is
C Insecticide
Thurioside is a toxin produced by the bacterium
Bacillus thuringenesis. It is used as an insecticide as it is highly effective against disease-causing insects like flies, moths, mosquitos etc. This toxin is produced in the form of crystal protein. The toxin helps by killing the pests or insects by inhibiting the transport of ion, formation of pores in the gut which finally results in bursting of cells. This gene for toxin is also introduced in transgenic plants which provide resistance to the crops from the pests.
Thus, the correct answer is option A.