Tobacco plants resistant to a nematode have been developed by the introduction of $DNA$ that produces (in the host cells):

Given below are $2$ statements: one is labelled as Assertion $(A)$ and other is labelled as Reason $(R)$.
Assertion $(A) :-$ Toxic insecticidal protein of Bacillus thuringiensis does not kill Bacillus itself.
Reason $(R) :-$ In Bacillus,$Bt$ toxin protein exists as inactive protoxins.
Correct answer from the options given below :

$Bt$ cotton variety that was developed by the introduction of toxin gene of $Bacillus$ $thuringiensis$ $(Bt)$ is resistant to

In plant cells,mutation can be induced by which of the following?

The bacterium $Bacillus$ $thuringiensis$ is widely used in modern biology as a/an:

The first transgenic plant developed was: