The first clinical gene therapy was given for treating

Which of the following is used for the treatment of genetic disorders?

In $1990$,which therapy was given to a four-year-old girl suffering from adenosine deaminase $(ADA)$ deficiency?

In $1983$,Eli Lilly,an American company,first prepared two $DNA$ sequences corresponding to $A$ and $B$-chains of human insulin and introduced them into the plasmids of $Escherichia$ $coli$ to produce insulin chains. Chains $A$ and $B$ were prepared separately,extracted,and combined by creating:

Statement-$I$: At present,$30$ recombinant therapeutics have been approved for human use the world over.
Statement-$II$: Recombinant therapeutics do not induce unwanted immunological responses,as is common in the case of similar products isolated from non-human sources.
Choose the correct answer from the options given below:

Which type of bond connects the $A$ and $B$ chains of human insulin?