According to 200.7(C)(1), how should a white or gray conductor used as a switch loop for circuits of 50 volts or more be reidentified?

The correct choice highlights that when a white or gray conductor is used as a switch loop in circuits of 50 volts or more, it must be reidentified to indicate its function accurately. This reidentification is crucial for safety and clarity in electrical installations, preventing confusion for anyone working on the electrical system.

Marking tape, painting, or using other effective means allows the conductor to be visually distinguished from typical white or gray wiring, thus communicating its purpose as a switch loop. This practice aligns with safety standards, ensuring that the electrical systems are properly documented and easily identifiable, reducing the risk of mishaps during maintenance or repairs.

This option emphasizes the importance of proper labeling in electrical work, which is essential for compliance with electrical codes and safe operation in buildings. The methods mentioned are practical and can be easily executed, making them preferred solutions in the industry.