This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cardiovascular system, Subject name: Physiology
The ECG change seen in hyperkalemia is 
Select and explain. 
A. Narrowing of the QRS complex, B. Increased amplitude of P waves, C. Narrowing and peaking of T waves, D. Ventricular arrhythmias
A: Narrowing of the QRS complex
Answer: A: Narrowing of the QRS complex 
Explanation: Hyperkalemia (plasma K+ +-7.0 meq/L). The PR and QRS intervals are within normal limits. Very tall, slender peaked T waves are now present. Hyperkalemia (plasma K+ +-8.5 meq/L). The QRS complex is broad and slurred and the QRS interval has widened to 0.2 s. The T waves remain tall and slender Fuher elevation of the plasma K+ level may result in ventricular tachycardia and ventricular fibrillation. Ref: Ganong's Review of Medical Physiology Twenty-Third Edition Page No: 504