Some of the characteristics of $Bt$ cotton are

Given below are two statements:
Statement $I$: $Bt$ toxins are insect group specific and coded by a gene $cry$ $IAc$.
Statement $II$: $Bt$ toxin exists as inactive protoxin in $B. \text{ thuringiensis}$. However, after ingestion by the insect, the inactive protoxin gets converted into active form due to alkaline $pH$ of the insect gut.
In the light of the above statements, choose the correct answer from the options given below:

Under what conditions does the inactive toxin of $Bt$ become active?

cry $II$ Ab and cry $I$ Ab produce toxins that control

$Meloidogyne$ $incognita$,which infects the roots of tobacco plants causing a great reduction in yield,is a:

The toxic $Cry$ protein is released by the spores of . . . . . . which kills the larvae of butterflies feeding on plants like $Brassica$.