$\alpha-1$ antitrypsin is

With regard to insulin,choose the correct options.
$(a)$ $C$-peptide is not present in mature insulin.
$(b)$ The insulin produced by $rDNA$ technology has $C$-peptide.
$(c)$ The pro-insulin has $C$-peptide.
$(d)$ $A$-peptide and $B$-peptide of insulin are interconnected by disulphide bridges.
Choose the correct answer from the options given below.

Why are genetically engineered lymphocytes periodically introduced into the patient in the treatment of $ADA$ deficiency?

Which of the following techniques serves the purpose of early diagnosis of $AIDS$,cancer,etc?
$I$. Polymerase chain reaction
$II$. Recombinant $DNA$ technology
$III$. Enzyme-linked immunosorbent assay
Choose the correct option.

Mention the importance of Recombinant $DNA$ technology in terms of vaccination.

Which one of the following is now being commercially produced by biotechnological procedures?