sentence2_structure: Electrical wires<>are covered<>with plastic or rubber<>to insulate the electrical wire<>usually
sentence1: Most are insulated with plastic or rubber coverings but occasionally you will find bare, tinned (solder coated), or plated copper wires.
sentence2: Electrical wires are usually covered with plastic or rubber to insulate the electrical wire.
question: Which of the following best explains why electrical wires are usually covered with plastic or rubber?