Which of the following is false for $Bt$ transgenic plants?

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

Which tool is most widely used in the genetic engineering of crop plants?

What are some of the characteristics of $Bt$ cotton?

Golden rice
$I$. It is a transgenic variety of rice.
$II$. It contains a good quality of $\beta$-carotene (provitamin-$A$).
$III$. $\beta$-carotene is a principal source of vitamin-$A$.
$IV$. The grains of the rice are yellow in colour due to $\beta$-carotene. The rice is commonly called golden rice.
Which of the statements given above are correct?

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