Map applications rely on which data source to determine location and routes?

• A. Satellite data
• B. Light from street lamps
• C. Audio signals from traffic lights
• D. Printed maps only

Answer: (A)

The main idea is that map apps determine where you are using signals from satellites. Your device listens to multiple satellites in orbit and measures how long their signals take to reach you. Those time measurements translate into distances to each satellite. With signals from at least four satellites, the device can solve for your exact position on Earth—your latitude, longitude, and altitude. Once the app knows where you are, it looks up the road network in its map data and computes a route to your destination using routing algorithms.

Other options don’t provide automatic location: street lamps give light, not your position; audio signals from traffic lights aren’t used to locate you; and printed maps don’t automatically supply your current location. Satellite data is the source that enables both knowing where you are and planning a route.