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. Hyperkalemia, B. Hyperkalemia, C. Hypermagnesemia, D. Hypocalcemia', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ref-KDT 6/e p499 Oxygen toxicity is a agravated by Hypokalemia and hypercalcemia', 'role': 'assistant'}]