The correct answer is D. wrapping an insulated wire around a metal with ferromagnetic properties and applying an electric current.
Step-by-step explanation
An electromagnet is a non permanent magnet that is created with an electric current .When current flows through a wire it induces a magnetic field around the wire. When the wire is wrapped around in a coil, the magnetic field that is induced is concentrated in the center of the coil, creating a north and south pole. The field is that of a solenoid.
Electromagnets are usually made by wrapping insulated coil of wire around a ferromagnetic metal. This focuses the electromagnetic field and creates a magnet as long as there is current running trough the insulated wire.
The correct answer is D. wrapping an insulated wire around a metal with ferromagnetic properties and applying an electric current.