Insulin Is a Small Protein That Regulates Blood Sugar Level

Insulin is a small protein that regulates blood sugar level and is given to patients who suffer from diabetes.Many years ago, diabetics were given insulin that had been purified from pig pancreas.Once recombinant DNA techniques became available, the DNA encoding insulin could be placed into an expression vector and insulin could be produced in bacteria.Which of the following is NOT a reason why purifying insulin from bacteria is a better way to produce insulin for diabetics than using insulin purified from a pig pancreas?

A) Insulin can be easily produced in large quantities from cells carrying the cloned DNA sequence.
B) The creation of transgenic pigs that expressed insulin was very expensive compared to the cost of creating bacteria that expressed insulin.
C) Insulin made from a bacterial culture and then purified will be free of any possible contaminating viruses that pigs (and any other animals) harbor.Since pigs are more closely related to people than bacteria are, their viruses are more likely to be harmful to people than are viruses that might infect bacteria.
D) The pig protein has slight amino acid differences compared to the human protein, so human insulin produced by bacteria will work better in people.