Proteolytic enzymes secreted from the pancreas are activated: a) within the lumen of the small intestine. b) once they reach the large intestine. c) in secretory vesicles within pancreatic secretory cells. d) once they reach the pancreatic duct.

A) within the lumen of the small intestine.

Explanation:

The pancreas produces a variety of hormone-like amylase, proteases, lipases which can digest the food material.

The proteases like chymotrypsinogen and trypsinogen are produced by the pancreas in their inactive form as if active will digest the organ itself. Therefore these zymogens are stored in the secretory vesicles which release the enzymes in the pancreatic duct.

These zymogens are not activated until they reach the digestive tract that is when these enzymes enter the lumen of the small intestine, the enterokinase present there catalyzes the trypsinogen to trypsin. Trypsin converts the chymotrypsinogen to the chymotrypsin.

Thus, Option-A is the correct answer.