The technique used to make numerous copies of a specific segment of $DNA$ quickly and accurately is

Main steps in the formation of Recombinant $DNA$ are given below. Arrange these steps in a correct sequence.
$A$. Insertion of recombinant $DNA$ into the host cell
$B$. Cutting of $DNA$ at specific location by restriction enzyme
$C$. Isolation of desired $DNA$ fragment
$D$. Amplification of gene of interest using $PCR$
Choose the correct answer from the options given below:

$A$ transformed bacterium with a human gene fails to produce the desired protein. The reason could be:

What type of vaccine is the Hepatitis $B$ vaccine?

Identify the correct sequence of steps in the Polymerase Chain Reaction $(PCR)$.

It is used to detect $HIV$ in suspected $AIDS$ patient and detect mutations in genes in suspected cancer patient too.