Question

The wire having a black plastic covering is a
(A) live wire
(B) neutral wire
(C) earth wire
(D) none of these

Answer 1

Hint
Black, Red and Blue are used for hot wires and White is used as the neutral wire in a 120/208 V circuit. Brown, Orange and Yellow are used as hot wires and gray is used as the neutral wire in a 277/480 V. The wire having a black plastic covering is a neutral wire.

Complete step by step answer
The neutral wire is often confused with ground wire, but in reality, they serve two distinct purposes. Neutral wires carry currents back to the power source to better control and regulate voltage. Its overall purpose is to serve as a path to return energy.
The wire having a black plastic covering is a neutral wire whereas that having a red covering is a live wire.

Note
A circuit is the path that an electric current travels on, and a simple circuit contains three components necessary to have a functioning electric circuit, namely, a source of voltage, a conductive path, and a resistor. Circuits are driven by flows.