In the treatment of $ADA$ deficiency during gene therapy,which cells are collected from the patient's blood?

Match the following and choose the correct option$-$

Column $I$	Column $II$
$(a)$ Eli Lilly	$(i)$ Bacillus thuringiensis
$(b)$ Bt	$(ii)$ Human insulin
$(c)$ Gene therapy	$(iii)$ Meloidogyne incognita
$(d)$ $\text{RNAi}$	$(iv)$ Adenosine deaminase deficiency

Sir Godfrey Hounsfield developed the diagnostic technique of

Which of the following is a main challenge for the production of insulin by the $r-DNA$ techniques?

What is produced from yeast?

Consider the following statements about insulin.
$I.$ Human insulin is made up of $51$ amino acids arranged in two polypeptide chains.
$II.$ The two polypeptide chains are interconnected by two disulphide bridges.
$III.$ In mammals,including humans,insulin is synthesised as a pro-hormone,which contains an extra stretch called the $C$-peptide.
$IV.$ $C$-peptide is not present in the mature insulin.
Which of the statements given above are correct?