In Gene cloning:

What is the process called when a foreign $DNA$ fragment replicates and multiplies automatically within a host organism?

Assertion : Insertion of recombinant $DNA$ within the coding sequence of $\beta -$ galactosidase results in colourless colonies.
Reason : Presence of insert results in inactivation of enzyme $\beta -$ galactosidase known as insertional inactivation.

With respect to $DNA$ fragmentation:
Statement $A$: Gel electrophoresis and elution are two important processes.
Statement $B$: After staining with ethidium bromide,it has to be exposed to $UV$ light.

$PCR$ (Polymerase Chain Reaction) is used for the diagnosis of which of the following diseases?

Which method is used to amplify a desired gene in large numbers?