a circuit a magnet a light bulb an insulator
I am hesitating between 4 options to answer the following question, which option should I choose?
Question: Marta has a radio in her room. It requires electricity in order to play. Which of the following is necessary in order for electricity to move from the source to the radio?
Possibilities:
- a circuit
- a magnet
- a light bulb
- an insulator

a circuit