Hypokalaemia is caused by the deficiency of ________.

Correct answer: Potassium

Explanation: ✅ Correct Answer: A) Potassium 📚 Explanation: Hypokalemia is a medical condition defined by abnormally low levels of potassium ($\text{K}^+$) ions in the human blood stream. Potassium is a vital electrolyte required for the proper functioning of nerve and muscle cells, especially in the heart. A severe deficiency can lead to muscle cramps, weakness, and dangerous heart arrhythmias. It is treated by eating potassium-rich foods like bananas or taking prescribed medical supplements.