This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Medicine
Tall ‘T’ waves are seen in: 
Select and explain. 
A. Hyperkalemia, B. Hypocalcemia, C. Hypercalcemia, D. Hypokalemia
A: Hyperkalemia
Answer: A: Hyperkalemia 
Explanation: Explanation: ECG changes in Hyperkalaemia Tall T waves
(Earliest sign) Prolonged PR interval Widened QRS interval Flattened P waves Arrythmias including bradycardia,
ventricular tachycardia or fibrillation Sinus arrest or nodal rhythm with possible asystole ECG changes
in Hypokalaemia Flattened T waves ST segment depression Prolonged QT interval Tall U waves Atrial arrythmias Ventricular tachycardia or ventricular fibrillation