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

In which therapeutic method is the functional $ADA-cDNA$ introduced into the patient's lymphocytes?

Some of the steps involved in the production of humulin are given below. Choose the correct sequence.
$(i)$ Synthesis of gene $(DNA)$ for human insulin artificially.
(ii) Culturing recombinant $E. coli$ in bioreactors.
(iii) Purification of humulin.
(iv) Insertion of human insulin gene into plasmid.
$(v)$ Introduction of recombinant plasmid into $E. coli$.
(vi) Extraction of recombinant gene product from $E. coli$.

Adenosine deaminase $(ADA)$ deficiency is most commonly caused by which genetic abnormality?

Which of the following are used in $MRI$ to detect physiological changes in living tissues?
$(i)$ $UV$ rays $(ii)$ Strong magnetic fields $(iii)$ $\gamma$-rays $(iv)$ $X$-rays

In $1983$, Eli Lilly, an American company, prepared two $DNA$ sequences corresponding to $A$ and $B$ chains of human insulin and introduced them in plasmids of which organism to produce insulin chains?