In which of the following are palindromic sequences present?

An enzyme catalysing the removal of nucleotides from the ends of $DNA$ is:

$A$ piece of foreign $DNA$ can replicate if it is linked to which of the following?

The enzymes which are absolutely necessary for recombinant $DNA$ technology are

The chemical knives of $DNA$ are:

Given below are two statements: one is labelled as Assertion $(A)$ and the other is labelled as Reason $(R)$.
Assertion $(A)$: When a particular restriction enzyme cuts a strand of $DNA$,overhanging stretches or sticky ends are formed.
Reason $(R)$: Some restriction enzymes cut the strand of $DNA$ a little away from the centre of the palindromic site.
In the light of the above statements,choose the correct answer from the options given below: