Which wave represents repolarization of the ventricles?

• A. QRS complex
• B. P wave
• C. T wave
• D. U wave

Answer: (C)

Ventricular repolarization is the heart’s ventricles resetting their electrical state after contraction, and it is represented on the ECG by the T wave. After the ventricles are activated during the QRS complex, potassium efflux and the return to the resting membrane potential produce the T wave as the ventricles finish their recovery. The P wave reflects atrial depolarization, not ventricular repolarization, and the QRS complex shows ventricular depolarization (activation). A U wave can appear in some conditions but is not the standard marker of normal ventricular repolarization.