Detailed Solution:
The correct answer is “Secretin”.
1) Renin is a hormone and enzyme produced in the kidneys that helps regulate blood pressure.
2) Trypsin is an enzyme that helps digest proteins in the small intestine.
3) Cholecystokinin (CCK) and secretin are the hormones that primarily regulate the production of pancreatic juice.
4) Pepsin is an enzyme secreted by the stomach that breaks down proteins in food into smaller pieces called polypeptides.