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
[{'content': 'Pepsin is activated by \nSelect and explain. \nA. HCI, B. Enterokinase, C. Uropepsinogen, D. Trypsinogen', 'role': 'user'}, {'content': 'Answer: A \nExplanation: The pepsin precursors are called pepsinogen and are activated by gastric acid.Pepsinogen 1 is found only in acid-secreting regions, whereas pepsinogen 2 is also found in the pyloric region.Pepsins have a pH optimum 1.6-3.2Pepsin hydrolizes the bonds between aromatic amino acids.(Ref: Ganong&;s Review of medical physiology, 23rd edition, page: 455)', 'role': 'assistant'}]