bare wire, plastic rod, battery bare wire, iron rod, light bulb insulated wire, iron rod, battery insulated wire, plastic rod, light bulb
I gave my students this multiple choice question: Which of the following groups of materials would most likely be used to build an electromagnet?

Only one answer is correct among these 4 choices:
- bare wire, plastic rod, battery
- bare wire, iron rod, light bulb
- insulated wire, iron rod, battery
- insulated wire, plastic rod, light bulb

Could you tell me which one is correct?

insulated wire, iron rod, battery