How is an electromagnet different from a magnet?
a
a magnet depends upon strength of the current.
b
an electromagnet can be changed by changing the amount of current.
c
an electromagnet does not have an insulated coil like a permanent magnet
d
an electromagnet has an iron core and can not be adjusted

b . An electromagnet can be changed by changing the amount of current.

Explanation:

In an electromagnet, the magnetic field is generated by an electric current in a coil of wire which reinforces an iron core. But when the electric current applied on the mentioned core is disconnected, it immediately loses its magnetization. This also means that the intensity of the magnetic field can be controlled (increased or decreased) by changing the intensity of the electric current flowing through the nucleus.

On the other hand, the permanent magnet does not depend on electric current to magnetize, because due to its composition (a ferromagnetic material) the magnetization capacity continues even after not being in contact with an external magnetic field.

answer: electrons