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
Glutathione reductase contains the following prosthetic group: 
Select and explain. 
A. FAD, B. NAD, C. ATP, D. None of the above
A: FAD
Answer: A: FAD 
Explanation: Glutathione reductase contains a flavoprotein containing FAD. Reduced glutathione removes H2O2 in a reaction catalyzed by glutathione peroxidase, an enzyme that contains the selenium analogue of cysteine (selenocysteine) at the active site. Ref: Harper 28th edition, chapter 21.