Transgenic plants are

Hirudin is

Cry proteins are obtained from $......$.

$A$: Production of hirudin from transgenic $Brassica$ required the use of a synthetic gene.
$R$: Eukaryotic genes have intron sequences that need to be spliced out.

Consider the following statements about $Bt$:
$I.$ The bacteria $Bacillus$ $thuringiensis$ $(Bt)$ are used to control butterfly caterpillars.
$II.$ Fresh spores of $Bt$ are mixed with water and sprayed on crops such as brassicas and fruit trees.
$III.$ Insect larvae,after eating these,are killed by the toxin released in their gut.
$IV.$ $Bt$ toxin genes have been introduced into plants to provide resistance to pests.
Which of the statements given above are correct?

In $BT$ Cotton,which of the following is true?