Passage Summary: Even though the actual fiber-optic wires cost more to make than copper ones, the total cost of the whole phone system is lower with fiber because you don't have to buy as many expensive signal-boosters for long distances.

Reasoning: Fiber-optic cable is more expensive to produce than copper, but fiber networks are cheaper overall because fiber signals travel much further than copper signals before they need to be amplified.

Analysis: We need to find a statement that must be true based on these facts. If the 'total' cost of a fiber network is lower despite the 'cable' cost being higher, the savings must be coming from the amplification side of the equation. This implies that the cost of installing and maintaining the frequent amplification required for copper is high enough to offset the initial savings on the copper cable itself. Look for an answer that compares the cost-efficiency of the two systems over long distances.