Which of the following helps in reducing the use of chemical pesticides?

$A$ - $A$ crop expressing a $cry$ gene is usually resistant to a group of insects.
$R$ - $Cry$ proteins produced from $Bacillus$ $thuringiensis$ are toxic to the larvae of certain insects.

What does $Bt$ stand for?

$Bacillus\, thuringiensis$ $(Bt)$ strains are used to design:

Which variety of cotton has been developed with the help of $Bacillus$ $thuringiensis$?

$A$ infects the roots of tobacco plants,which reduces the production of tobacco.