How many of the following statements are correct?
$(i)$ Mature insulin is made up of $A, B$ and $C$ peptides.
$(ii)$ Removal of $C$-peptide helps in the maturation of insulin.
$(iii)$ In mature insulin,$C$-peptide is present.
$(iv)$ In insulin,chains $A$ and $B$ are linked by disulphide bonds.

The disadvantage of using porcine insulin in diabetic patients is

Which of the following methods,other than gene therapy,has been used for the treatment of $ADA$ deficiency?

Statements related to human insulin are given below. Which statement$(s)$ is/are correct about genetically engineered insulin?
$(a)$ Pro-hormone insulin contains an extra stretch of $C$-peptide.
$(b)$ $A$-peptide and $B$-peptide chains of insulin were produced separately in $E. coli$,extracted,and combined by creating disulfide bonds between them.
$(c)$ Insulin used for treating diabetes was extracted from cattle and pigs.
$(d)$ Pro-hormone insulin needs to be processed for converting into a mature and functional hormone.
$(e)$ Some patients develop allergic reactions to the foreign insulin.
Choose the most appropriate answer from the options given below:

Injecting functional adenosine deaminase into a patient's (lacking $ADA$ gene) blood cells may be considered as

Humulin is . . . . . . .