Although fiber-optic telephone cable is more expensive to manufacture than copper telephone cable, a telephone network using fiber-optic cable is less expensive overall than a telephone network using copper cable. This is because copper cable requires frequent amplification of complex electrical signals to carry them for long distances, whereas the pulses of light that are transmitted along fiber-optic cable can travel much farther before amplification is needed. The above statements, if true, most strongly support which one of the following? ['Signals transmitted through fiber-optic cable travel at the same speed as signals transmitted through copper cable.', 'The cost associated with frequent amplification of signals traveling through copper cable exceeds the extra manufacturing cost of fiber-optic cable.', 'The material from which fiber-optic cable is manufactured is more expensive than the copper from which copper cable is made.', 'The increase in the number of transmissions of complex signals through telephone cables is straining those telephone networks that still use copper cable.']