Advances in technology have led to the replacement of conventional electrical wires with networks of fiber-optic cable for transmitting telecommunications signals. However there is a limitation with fiber-optic cables. Signals running through them deteriorate progressively necessitating boosters called regenerator. Xenon Inc, a Finnish firm, is the world's leading manufacturer of signal regenerators. Therefore, there is no doubt that Xenon Inc would benefit immensely if new long-distance fiber-optic telecommunications networks are constructed.
Which of the following, if true, casts the most doubt on the prediction about Xenon's prospects?

A. Signals in electrical wires travel much farther than signals in fiber-optic networks before needing to be regenerated.
B. Xenon Inc needs to spend proportionately more on labor and materials if it has to increase the production of regenerators.
C. The volume of signals that a fiber-optic cable can carry is several thousand times greater than the volume that can be carried by an electrical wire of similar size.
D. There are technologies that enable telecommunications signals to be transmitted without either wire or fiber-optic cable.
E. Several manufacturers are developing regenerator technologies that will allow signals to be transmitted many times farther than at present before requiring regeneration