Answer: The correct answer is "The switch is closed, completing the circuit".
Step-by-step explanation:
Electromagnet: It is a temporary magnet. When the iron rod is wounded by the coils and the current is passed through it then it becomes magnetized and behave like a temporary magnet as long as the current flows through it.
When you push the button of a doorbell then the circuit completes and the current starts flowing through the circuit. The electromagnet is activated.
It causes a buzzer to go off. The hammer strikes the bars which creates sound.
Therefore, the correct answer is "The switch is closed, completing the circuit".