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

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.

Match the following columns:

List-$I$	List-$II$
$(a)$ $1977$	$(1)$ Creation of the first transgenic cow
$(b)$ $1983$	$(2)$ American company obtained patent for Basmati rice
$(c)$ $1990$	$(3)$ Eli Lilly company prepared two $DNA$ sequences for insulin
$(d)$ $1997$	$(4)$ First clinical gene therapy trial

The first clinical gene therapy was given in $1990$ to a $4$-year-old girl for the treatment of which disease?

Which country's company first produced human insulin?

Maturation of proinsulin into insulin takes place after