This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Metabolism of protein and amino acid, Subject name: Biochemistry
True about glutathione is 
Select and explain. 
A. 4 amino acids, B. Gamma peptide, C. Alpha peptide, D. 3 amino acids
D: 3 amino acids
Answer: D: 3 amino acids 
Explanation: Glutathione -tripeptide-also called gamma-glutamyl cysteinyl glycine. It consists of 3amino acids glutamic acid, glycine, &cystein. It is produced from miester cycle (gamma-glutamyl cycle)catalysed by gamma-glutamyl transferase.Ref: DM Vasudevan - Textbook of Biochemistry for Medical Students, 7th edition, page no: 198