This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Fluid and electrolytes, Subject name: Medicine
[{'content': 'Hypokalemia is defined as a plasma potassium concentration of \nSelect and explain. \nA. < 3.5 mmol/L, B. < 3.6 mmol/L, C. < 3.7 mmol/L, D. < 3.8 mmol/L', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Hypokalemia, defined as a plasma K+ concentration of <3.5 mM, Hyperkalemia is defined as a plasma potassium level of 5.5 mM Ref: Harrison 19e pg: 305', 'role': 'assistant'}]