Why Is Insulin Produced by Genetically Engineered E

Why is insulin produced by genetically engineered E.coli cells superior to insulin obtained from animal sources?

A) Animal insulin has a shorter life span than insulin produced using recombinant DNA techniques.
B) It contains human rather than animal sequences, reducing the chances of an allergic response.
C) Animal insulin is more difficult to purify than is recombinantly produced insulin.
D) Recombinantly produced insulin has a much higher activity level.
E) Recombinantly produced insulin is easier to obtain than insulin from animals.