This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Proteins and Amino Acids, Subject name: Biochemistry
[{'content': 'Glutathione is a: \nSelect and explain. \nA. Monopeptide, B. Dipeptide, C. Tripeptide, D. Tetrapeptide', 'role': 'user'}, {'content': 'Answer: C \nExplanation: C Harper, 26th ed, p. 629 & 25th ed, p. 38, Fig (5.4)', 'role': 'assistant'}]