Final answer:
The statement about high-voltage wires being wrapped in an insulating material is false. They are bare and are held aloft by insulators that prevent the current from reaching the towers.
Step-by-step explanation:
The statement that the high-voltage wires connected to tall metal-frame towers are wrapped in an insulating material is false. High-voltage wires are actually bare and not insulated. The reason they do not need an insulating cover is that the air provides enough of an insulating barrier to prevent the current from arcing to the towers. However, these wires are indeed held aloft by insulating connectors called insulators, which prevent the electricity from traveling down the towers to the ground.