Please choose the correct answer to the question: Alex looked at an electric toothbrush that had a plug with three metal prongs. Why are these prongs made out of metal?

Answer1: Metal doesn't get hot and melt when you plug it into the outlet. Answer2: Metal is strong and is less likely to break when you plug it into the outlet. Answer3: Metal is an insulator and prevents shocks when you plug it into the outlet. Answer4: Metal is a conductor and completes a circuit when you plug it into the outlet.

Answer format: answer1/answer2/answer3/answer4
Answer: answer4