This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Fluids and Electrolyte Imbalance, Subject name: Medicine
Patient develops vomiting episodes and extreme muscle weakness. Cause is? 
Select and explain. 
A. Hypokalemia, B. Hyponatremia, C. Hypophosphatemia, D. Hypomagnesemia
A: Hypokalemia
Answer: A: Hypokalemia 
Explanation: Vomiting - Dehydration - Low GFR - stimulate RAAS mechanism- | Aldosterone | (Hypokalemic Alkalosis) Hypokalemia- Muscle weakness (Diaphragmatic paralysis) Hyponatremia - Seizures Hypomagnesemia - Tetany