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

What is the toxic protein produced in $Bacillus \text{ } thuringiensis$ called?

$A$ - $A$ 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.

The vector commonly used for transformation in crop plants is ......

Which part of the tobacco plant is infected by $Meloidogyne \ incognita$?

Consumption of which one of the following foods can prevent the kind of blindness associated with vitamin $A$ deficiency?