Which of the following enzymes are used to join bits of $DNA$?

The discovery of which of the following has made it possible to cut $DNA$ at specific locations?

Select the incorrect statement.

Plasmid of which bacterium was first time used in recombinant $DNA$ technology?

$A$: Restriction enzymes belong to a larger class of enzymes called nucleases.
$R$: Each restriction enzyme recognizes a specific palindromic nucleotide sequence in the $DNA$.

Which one of the following represents a palindromic sequence in $DNA$?