This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Biochemistry
[{'content': 'In glutathione which amino acid is reducing agent \nSelect and explain. \nA. Glutamic acid, B. Glycine, C. Cysteine, D. Alanine', 'role': 'user'}, {'content': 'Answer: C \nExplanation: The sulphydryl (-SH) group of cysteine residue is the reactive portion of glutathione which can undergo oxidation and reduction.', 'role': 'assistant'}]