This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: nutrition and digestion, Subject name: Biochemistry
The serine proteases are all except 
Select and explain. 
A. Elastase, B. Chymotrypsin, C. Trypsin, D. Pepsin
D: Pepsin
Answer: D: Pepsin 
Explanation: They are enzymes with a serine residue at the active site and most of the proteolytic enzymes belong to this group, e.g. trypsin, chymotrypsin, clotting factors. Ref: DM Vasudevan, page no: 44