The colour of the earth wire is generally:

There are typically three different types of wires in plug wiring. Each of these wires has a distinct color and is distinguished as an active wire, a neutral wire, and a ground wire.
The majority of live wires employ an RGB (red, blue, and green) mix of wire colors.
In a live stream, the ground wire is often green in color. The current in the circuit is grounded using grounding wires. This implies that to protect the circuit from electrical shocks, the grounding wire transfers all of the circuit's charge to the ground while the circuit's switch is off.

In three-pin sockets when high-power need equipment is connected, ground wires are typically visible. This guarantees that any circuit leakage that occurs while the appliance is being used is contained and sent to the ground.
Since switches for lights and fans operate at lower voltages and with less power, we won't locate grounding cords in them. However, for safety reasons, equipment like microwaves, refrigerators, etc. require a grounding connection.

Hence, the correct answer is option D.