Given below are two statements: Statement I: B t toxin protein exists as inactive protoxins in Bacillus thuringiensis. Statement II: The inactive protoxin is activated by the acidic pH of the insect's midgut, which solubilizes the crystals and leads to pore formation. In the light of the above statements, choose the most appropriate answer from the options given below:

Step-by-step solution

Statement I is correct because the B t toxin is produced in an inactive form called protoxin in the bacterium Bacillus thuringiensis, which prevents the bacterium from being killed by its own toxin. Statement II is incorrect because the inactive protoxin requires an alkaline pH (not acidic pH) in the insect's midgut to solubilize the crystals and become an active toxin. The active toxin then binds to the midgut epithelial cells, creating pores that cause cell swelling and lysis. Answer: Statement I is correct but S