bold face - Modern navigation systems

Modern navigation systems, which are found in most of today’s commercial aircraft, are made with low-power circuitry, which is more susceptible to interference than the vacuum-tube circuitry found in older planes. During landing, navigation systems receive radio signals from the airport to guide the plane to the runway. Recently, one plane with low-power circuitry veered off course during landing, its dials dimming, when a passenger turned on a laptop computer. Clearly, modern aircraft navigation systems are being put at risk by the electronic devices that passengers carry on board, such as cassette players and laptop computers.

The two portions in boldface play which of the following roles?
(A) The first is a principle that the argument relies on and the second is a conclusion that can be drawn from the first.
(B) The first is a fact that argument relies on and the second is a conclusion that must be drawn from this argument.
(C) The first acknowledges a consideration that supports that main position; the second is that conclusion.
(D) The first is an evidence that supports the conclusion, the second is that conclusion.
(E) The first is a principle that is necessary for this argument, the second is a conclusion that could be drawn from this argument.

pls explain the answer and why other options seem to be incorrect. Will post the OA after some discussion.....thnx