This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Fluid and electrolytes, Subject name: Medicine
Prominent U waves on the ECG is a feature of - 
Select and explain. 
A. Hyponatremia, B. Hypernatremia, C. Hypokalemia, D. Hyperkalemia
C: Hypokalemia
Answer: C: Hypokalemia 
Explanation: Electrocardiographic changes in hypokalemia include broad flat T waves, ST depression, u wave and QT prolongation. (reference: harrisons principles of internal medicine,19E page-307)