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
Mg is use in Rx of- 
Select and explain. 
A. Diarrhea, B. Tetany, C. Intractable seizures, D. Cardiac arrest
B: Tetany
Answer: B: Tetany 
Explanation: Normal concentration of extracellular magnesium and calcium are crucial for normal neuromuscular activity ( Harrison 20th editionpg 2372)