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': 'These ECG changes are seen in <img src=" /> \nSelect and explain. \nA. Hyponatremia, B. Hypernatremia, C. Hypokalemia, D. Hyperkalemia', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Electrocardiographic changes in hypokalemia include broad flat T waves, ST depression, prominent U waves (best seen in the precordial leads) and QT prolongation; these are most marked when serum K+ is <2.7 mmol/L. Ref: Harrison 19e pg: 307', 'role': 'assistant'}]