What is the advantage of a GPS-satellite system compared to other navigational aids?

A、TheGPSsystemisbasedonhyperbolanavigation.
B、TheGPSsystemgivesinformationaboutposition,speedandtimecontinuouslyworldwide.
C、TheGPSsystemgivesinformationaboutweather-andwaveconditionsinanarea.
D、The·GPSsystemhasbuiltinagroupofsixradiobeaconscalledaDecca-chain.