Which enzyme is required to obtain $DNA$ in its pure form from a cell?

Separation of $DNA$ fragments is done by a technique known as:

From the following tools/techniques of genetic engineering,identify those which are required for cloning a bacterial gene in animal cells and choose the correct option:
$I$. Endonuclease $II$. Ligase
$III$. $A. tumefaciens$ $IV$. Microinjection
$V$. Gene gun $VI$. Lysozyme
$VII$. Cellulase $VIII$. Electrophoresis

Consider the following figure of a stirred-tank bioreactor and identify $A, B, C$,and $D$.

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.

What is the process of electroporation?