to insulate the electrical wire to keep the electrical wire warm to make the electrical wire stronger to make the electrical wire more flexible
I am hesitating between 4 options to answer the following question, which option should I choose?
Question: Which of the following best explains why electrical wires are usually covered with plastic or rubber?
Possibilities:
- to insulate the electrical wire
- to keep the electrical wire warm
- to make the electrical wire stronger
- to make the electrical wire more flexible

to insulate the electrical wire