This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Respiratory chain, Subject name: Biochemistry
[{'content': 'Reduction potential of potassium is \nSelect and explain. \nA. -2.93, B. -0.44, C. -0.34, D. 0.54', 'role': 'user'}, {'content': 'Answer: A \nExplanation: K+ + e- = K(s) -2.93', 'role': 'assistant'}]