Which of the following is a hormone?

Explanation

Insulin is an animal hormone secreted by the beta ($\beta$) cells of the islets of Langerhans of the endocrine part of the pancreas. In terms of chemical structure, insulin is a peptide hormone, formed from amino acids. It regulates the metabolism of glucose (carbohydrates), fats, and proteins in the body. Due to deficiency of insulin, a person suffers from diabetes. ## Page 21