Given the fact "An electrical conductor is a vehicle for the flow of electricity", what is the answer to the question or completion "How can it be shown that an electrical conductor is a vehicle for the flow of electricity?"

Options: 1. holding an electrified fence can kill you 2. electricity is unable to conduct well through rubber shoe soles 3. sticking a fork into an electrical outlet is safe if it is plastic 4. electricity is a volatile thing
1.