Which of the Following Statements Is True of Insulin

Which of the following statements is true of insulin?

A) Insulin strands consist of bridges formed by the bonding of sulfur groups in cysteine molecules.
B) Insulin is an essential amino acid and should be consumed regularly through the diet.
C) A change in the amino acid sequence of insulin causes sickle-cell disease.
D) Insulin is a primary protein found in bones and ligaments.
E) Human insulin strands are made up of only one type of amino acid.