Final answer:
Ghrelin is the peptide hormone produced in the stomach that stimulates appetite, signaling when you are hungry.
Step-by-step explanation:
The peptide hormone produced in the stomach that stimulates appetite is ghrelin. Ghrelin is secreted when the stomach is empty, and it signals the brain to induce the feeling of hunger. Other hormones mentioned, such as cholecystokinin and gastric inhibitory polypeptide, have different roles in the body. For instance, cholecystokinin is involved in stimulating the release of pancreatic enzymes and bile, while gastric inhibitory polypeptide slows down gastric secretion and peristalsis when fatty acids and sugars are present.