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
[{'content': 'The serine proteases are all except \nSelect and explain. \nA. Elastase, B. Chymotrypsin, C. Trypsin, D. Pepsin', 'role': 'user'}, {'content': 'Answer: D \nExplanation: 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', 'role': 'assistant'}]