This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: G.I.T., Subject name: Physiology
Enterokinase is an activator of: 
Select and explain. 
A. Trypsinogen, B. Trypsin, C. Chymotrypsin, D. Antitrypsin
A: Trypsinogen
Answer: A: Trypsinogen 
Explanation: Ans. A TrypsinogenRef: Ganongy 25th ed. pg 479* Trypsinogen is converted to active enzyme trypsin by enterokinase when the pancreatic juice enters into the duodenum. Enterokinase contains 41% polysaccharide and this high polysaccharide content prevents the enterokinase from getting digested.* The trypsin, chymotrypsin and elastase act at interior peptide bonds in the peptide molecules and are called as endopeptidases.