What does a ground fault circuit interrupter do?

A ground fault circuit interrupter (GFCI) plays a crucial role in electrical safety by monitoring the flow of electricity. If it detects an imbalance in the incoming and outgoing current, which may indicate that some of the current is leaking to the ground (potentially through a person), it responds by interrupting current flow very quickly. This rapid disconnection can happen in a fraction of a second, significantly reducing the risk of electric shock or electrocution in environments where water is present, such as bathrooms or kitchens.

The other options describe functions that are not the primary purpose of a GFCI. Increasing power supply, converting AC to DC, and regulating voltage output involve different types of devices and systems not associated with the protective function of a GFCI. Thus, the correct answer accurately captures the critical safety role that a ground fault circuit interrupter serves in preventing electrical hazards.