Answer: The correct answer is "iron rod".
Step-by-step explanation:
Electromagnet is not a permanent magnet. The electromagnet consists of wrapping the coils around the iron rod.
When the current passes through it it will retain its magnetic property. Iron retains the magnetic property as the current flows in the electromagnet. Iron is a ferromagnetic material.
It will loose its magnetism easily when the power is switched off.
The strength of the magnetism depends on the number of turns and the amount of current flowing through it.
Therefore, the correct option is (C).