The correct option is A Enterokinase : trypsinogen
Trypsinogen is the precursor form of the pancreatic enzyme trypsin. It is found in pancreatic juice along with amylase, lipase, and chymotrypsinogen. It is activated by enterokinase which is found in the intestinal mucosa to form trypsin. The relation between enterokinase to trypsin is same as HCl to pepsinogen, because HCl activates pepsinogen to pepsin, in the stomach.