This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: C.V.S, Subject name: Medicine
All are ECG changes hypokalemia,except- 
Select and explain. 
A. U wave, B. ST segment sagging, C. T-wave flattening or inversion, D. QT interval prolongation
D: QT interval prolongation
Answer: D: QT interval prolongation 
Explanation: Multiple medications, electrolyte abnormalities (hypocalcemia, hypomagnesemia and hypokalemia) and ceain disease states (ie, intracranial hemorrhage) can prolong the QT interval. Prolonged QT genetic syndromes exist and include Romano-Ward syndrome, Jervell-Lange-Nielsen syndrome and long-QT syndrome. Ref Harrison 20th edition pg 1445