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?

• A
  $I, II, III, IV$
• B
  $I, IV, III, II$
• C
  $III, IV, II, I$
• D
  $I, III, IV, II$