The correct answer is: A. Gastrin
Gastrin is a hormone that stimulates the secretion of gastric acid and pepsin from the stomach. It is also involved in the regulation of gastric emptying and the secretion of bile.
Pepsin is an enzyme that breaks down proteins into smaller peptides. It is produced by the chief cells of the stomach.
Amylase is an enzyme that breaks down starch into glucose. It is produced by the salivary glands and the pancreas.
Lipase is an enzyme that breaks down lipids into fatty acids and glycerol. It is produced by the pancreas.
Gastrin is a digestive hormone because it stimulates the secretion of gastric acid and pepsin, which are both involved in the digestion of food.