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
Glutathione is a: 
Select and explain. 
A. Monopeptide, B. Dipeptide, C. Tripeptide, D. Tetrapeptide
C: Tripeptide
Answer: C: Tripeptide 
Explanation: C Harper, 26th ed, p. 629 & 25th ed, p. 38, Fig (5.4)