This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Oncology, Subject name: Medicine
[{'content': 'A 60-year-old woman with heart failure and normal renal function is started on furosemide (Lasix) 80 mg/day. She notices a good diuretic response every time she takes the medication. A few weeks later, she is feeling unwell because of fatigue and muscle weakness, but her heart failure symptoms are better. Which of the following is the most likely explanation for her muscle weakness? \nSelect and explain. \nA. hyponatremia, B. hypernatremia, C. hypokalemia, D. hyperkalemia', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Hypokalemia can result in paralytic ileus, rhabdomyolysis, weakness, and cardiac repolarization abnormalities. It is a common complication along with hyponatremia of starting patients on diuretics.', 'role': 'assistant'}]