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: Pathology
All of the following enzymes may contribute in generating free oxygen radicals within neutrophils for killing intracellular bacteria, except: 
Select and explain. 
A. Superoxide Dismutase, B. Fenton's reaction, C. NADPH oxidase, D. Glutathione Peroxidase
D: Glutathione Peroxidase
Answer: D: Glutathione Peroxidase 
Explanation: Glutathione peroxidase is an enzyme which works as an antioxidant. It catalyses the reaction in which H2O2 is conveed into water. So it does not generate free radicals. Ref: Robbins pathologic basis of disease 6th edn/page 12,13,14.