Final answer:
The repolarization of an autorhythmic cell is due to the opening of voltage-gated potassium channels, which allow potassium ions to leave the cell and restore the resting potential.
Step-by-step explanation:
The repolarization of an autorhythmic cell is due to the opening of voltage-gated potassium channels. These channels open when the membrane potential reaches a specific voltage, allowing potassium ions to leave the cell and restore the resting potential. During repolarization, the voltage-gated sodium channels close, preventing further influx of sodium ions.