The enzyme $(a)$ is needed for isolating genetic material from plant cells and enzyme $(b)$ for isolating genetic material from fungus. Choose the correct pair of options from the following:

The different basic steps of genetic engineering are given below randomly:
$I.$ Identification of $DNA$ with desirable genes
$II.$ Gene transfer
$III.$ Maintenance of $DNA$ in host and gene cloning
$IV.$ Introduction of $DNA$ into host to form recombinant $DNA$
Which of the following represents the correct sequence of steps?

Transformation is a process in which ..........

When a foreign $DNA$ is introduced into an organism,how is it maintained in the host and how is it transferred to the progeny of the organism?

Downstream processing includes:
$I.$ Separation of the product from the reactor
$II.$ Purification of the product
$III.$ Formulation of the product with suitable preservatives
$IV.$ Quality control testing and clinical trials in case of drugs
Which of the statements given above are correct?

$A$ : Taq Polymerase is involved in $PCR$ technique.
$R$ : This enzyme remains active during the high temperature including denaturation of double stranded $DNA$.