Abaseline for an experimental investigation is provided by the ? ?

We all use gps today, even if we don't drive yet. i bet you have been in the car with a parent and they have asked you to get out your phone to find a specific location. in your car, on the phone, you are using a very sophisticated technology. gps satellites circle the earth twice a day in a very precise orbit and transmit signal information to earth. gps receivers take this information and use trilateration to calculate the user's exact location. essentially, the gps receiver compares the time a signal was transmitted by a satellite with the time it was received. the time difference tells the gps receiver how far away the satellite is. now, with distance measurements from a few more satellites, the receiver can determine the user's position and display it on the unit's electronic map. what type of signal is utilized by the gps satellite?

Asun-sized star will spend most of its lifetime as a: white dwarf red giant protostar main-sequence star

Abearing is designed to a reduce friction b. support a load c. guide moving parts such as wheels, shafts and pivots d. all of the above