This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Enzyme Kinetics, Subject name: Biochemistry
Which of the following enzymes is stable at acidic pH: 
Select and explain. 
A. Pepsin, B. Trypsin, C. Chymotrypsin, D. Carboxypeptidase
A: Pepsin
Answer: A: Pepsin 
Explanation: Ans. A. PepsinPepsin is formed when pepsinogen is activated by hydrochloric acid in the stomach. The optimum pH for pepsin action is 1.6 to 3.2.