In mature insulin,chain $A$ and chain $B$ are interlinked by which bond?

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.

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.

Identify the incorrect statement.

$ELISA$ is based on:

Which of the following peptide chain is removed during the maturation of proinsulin into insulin?