This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Nutrition, Subject name: Medicine
[{'content': 'Mg is use in Rx of- \nSelect and explain. \nA. Diarrhea, B. Tetany, C. Intractable seizures, D. Cardiac arrest', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Normal concentration of extracellular magnesium and calcium are crucial for normal neuromuscular activity ( Harrison 20th editionpg 2372)', 'role': 'assistant'}]