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
[{'content': 'All of the following cause Ischemic Reperfusion Injury by generating ROS, except: \nSelect and explain. \nA. Incomplete redox reactions by damaged mitochondria, B. Compromised cellular antioxidant defense mechanisms, C. Infiltrating leukocytes, D. Activation of the complement system', 'role': 'user'}, {'content': 'Answer: D \nExplanation: New damage may be initiated during reoxygenation by increased generation of ROS. Some of the ROS may be generated by injured cells with damaged mitochondria that cannot carry out the complete reduction of oxygen.\nCellular antioxidant defense mechanisms may be compromised by ischemia, exacerbating the situation.\xa0\nROS generated by infiltrating leukocytes also may contribute to the damage of vulnerable injured cells.\nActivation of the complement system also\xa0may\xa0contribute\xa0to\xa0ischemia-reperfusion\xa0injury. Complement proteins may bind to the injured tissues, or\xa0to\xa0antibodies\xa0that\xa0are\xa0deposited\xa0in\xa0the\xa0tissues,\xa0and subsequent\xa0complement\xa0activation\xa0generates\xa0byproducts that exacerbate the cell injury and inflammation.', 'role': 'assistant'}]