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
[{'content': 'H2S inhibits which complex of ETC \nSelect and explain. \nA. I, B. II, C. III, D. IV', 'role': 'user'}, {'content': "Answer: D \nExplanation: Ans. is `d' i.e., IV", 'role': 'assistant'}]