What is the global positioning system? describe how it might be used by a hiker lost in the woods?

GPS is a system made up of three parts (satellites, ground stations, and receivers) that help in determining ground location with incredible precision. The satellites continuously transmit a signal and its receiver calculates its distance from the satellite. The positions of the satellites are used by the receivers as reference points to determine the location of the GPA receiver.

For instance, when a hiker gets lost in the woods and has access to a GPS receiver, he will easily be able to determine his current location. Marking his starting location on a GPS receiver will also assist him into finding his way back. 

competition i thin

it should be d or b but i'm sure it's d