This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Pathology
[{'content': 'A reactant generated by neutrophils that plays an impoant role in bacterial killing is \nSelect and explain. \nA. NADPH oxidase, B. Hexose monophosphate shunt, C. G proteins, D. Superoxide anion', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Superoxide anion is generated when oxygen is reduced by cytoplasmic NADPH. The reduction is carried out by the enzyme NADPH oxidase, which is not a reactant but a catalyst activated in cells responding to bacteria.', 'role': 'assistant'}]