This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Medicine
[{'content': 'All of the following may precipitate digitalis toxicity except - \nSelect and explain. \nA. Hypocalcemia, B. Hypokalemia, C. Hypomagnecemia, D. Hypothyroidism', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]