$\begin{array}{1 1} \text{a. The inactive protoxin gets converted into active form in insect gut} \\ \text{b. Bt. Roxin exists as active toxin in bacillus. The activated toxin enters the ovaries of the pest and sterilize it thus preventing their multiplication} \\ \text{c. The concerned bacillus has anti toxins} \\ \text{d. Reverse transcriptase} \end{array} $
