This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cardiovascular system, Subject name: Pharmacology
[{'content': 'Digoxin toxicity is aggravated by? \nSelect and explain. \nA. Hypokalemia, B. Hyperkalemia, C. Hypercalcemia, D. Hypocalcemia', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Digoxin toxicity causes hyperkalemia, or high potassium. The sodium/potassium ATPase pump normally causes sodium to leave cells and potassium to enter cells. Blocking this mechanism results in higher serum potassium levels (REF.Essentials of medical pharmacology K D TRIPATHI 8th Edition)', 'role': 'assistant'}]