The best answer is "a" - DNA.
Insulin is a protein that is secreted or produced by special cells called beta cells found in the pancreas.
The information for synthesizing insulin protein is found in the DNA of the beta cells. These cells are specifically located in what are called the islets of Langerhans in the pancreas.
Insulin is a protein hormone made up 51 amino acids and has a molecular weight of about 5808 Da.
Insulin helps in regulation of glucose levels in the body.
