Tracking Capabilities of Satellites & Function of GPS

Q. <!--td {border: 1px solid #ccc;}br {mso-data-placement:same-cell;}--> In which year did GPS become open for public use?

1. 1979
2. 1980
3. 1981
4. 1982

Q. <!--td {border: 1px solid #ccc;}br {mso-data-placement:same-cell;}--> What sort of information does the GPS show?

1. Population
2. Location
3. Elevation
4. Longitude

Q. <!--td {border: 1px solid #ccc;}br {mso-data-placement:same-cell;}--> From where does a GPS receiver receive its signal?

1. Towers
2. Underwater cables
3. Interconnection of electronic devices
4. Satellites