Which electrolyte imbalance is most likely indicated by a peaked T wave on an ECG?

Rationale: A tall, peaked T wave on an ECG is a classic sign of elevated potassium levels, which can progress to life-threatening arrhythmias if untreated. B. Hypocalcemia is incorrect; it is associated with prolonged QT intervals and tetany, not peaked T waves. C. Hyponatremia is incorrect; it typically causes neurologic symptoms (confusion, seizures) rather than characteristic ECG changes. D. Hypomagnesemia is incorrect; it can cause prolonged QT and torsades de pointes, but not peaked T waves.