Which pancreatic enzyme is primarily responsible for activating other pancreatic zymogens (e.g., trypsinogen) in the small intestine?

• A. Lipase is the major activator of trypsinogen in the intestinal lumen and therefore initiates protease cascades.
• B. Pepsin directly activates pancreatic zymogens within the stomach lumen before they enter the small intestine.
• C. Amylase converts trypsinogen into trypsin by cleaving carbohydrate moieties on the zymogen, allowing activation.
• D. Enteropeptidase (enteropeptidase in the brush border) activates trypsinogen to trypsin, which then activates other zymogens.

Answer: (D)