This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: ETC, Subject name: Biochemistry
[{'content': 'Which of the component of respiratory chain reacts directly with molecular oxygen: \nSelect and explain. \nA. Cyt b, B. CoQ, C. Cyt C, D. Cyt aa3', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Cyt aa3 is complex IV of ETC, which directly reacts with oxygen. ETC Complex Components Complex I FMN + Fe-S Complex Complex II FAD + Fe - S Complex Complex III Cyt b, Fe-S Complex Complex IV Cyt aa3, Cu', 'role': 'assistant'}]