In the $RNAi$ method,what is the source of the complementary double-stranded $RNA$?

Desired genes have been introduced into transgenic animals to obtain large-scale production of useful biological products encoded by these genes. This approach is generally referred to as

$ELISA$ method works on which of the following principles?

Human insulin is being commercially produced from a transgenic species of

$\alpha-1$ antitrypsin is used to treat which disease?

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?