Which of the following requirements must be met for a branch circuit supplying a residential bathroom?

For a branch circuit supplying a residential bathroom, all specified requirements are essential to ensure safety and compliance with electrical codes.

The circuit must be dedicated to the bathroom because this ensures that its capacity is not shared with other rooms that may have different electrical needs, which is vital in spaces that are often wet and can pose a higher risk of electrical shock. A dedicated circuit helps to minimize the risk of overloads and ensures that all outlets in the bathroom are adequately powered.

Providing at least 20 amps is an important requirement as bathrooms typically require the capacity to handle multiple devices, such as hair dryers or space heaters, which can demand significant power. Having a circuit rated for 20 amps ensures that it can safely meet the needs of typical bathroom devices without tripping or causing electrical hazards.

GFCI (Ground Fault Circuit Interrupter) protection is critical in bathrooms due to the proximity to water. GFCI devices help prevent electrical shock by quickly cutting off power in the event of a ground fault, thus enhancing the safety of electrical installations in moist environments.

By meeting all these requirements, the circuit can ensure both functionality and safety in a residential bathroom setting, which is why the comprehensive choice of all options being correct is indeed validated.