Which of the following may be used as a neutral wire?

In electrical systems, the neutral wire serves an essential role in completing the circuit by providing a return path for electric current. It is typically color-coded for easy identification. The established standard in electrical wiring is that neutral wires are always colored white or light gray.

This coding helps ensure that anyone working with electrical systems can quickly and easily identify the role of each wire. Black is often used for hot wires, red can also denote hot wires or second hot wires in 220-volt systems, and green typically signifies a ground wire. Consequently, choosing white as the neutral wire aligns perfectly with these established conventions, making it the correct answer.

Understanding the color coding and function of each wire is crucial for safety and compliance with electrical codes, especially in scenarios involving installation, maintenance, or troubleshooting of electrical systems.