Select the correct text in the passage.
Jonah is reading a blog post on the history of GPS, but he's pretty sure it is mostly unreliable. Can you find the one reliable sentence in the post?
The Global Positioning System (GPS) was first used by the US Air Force as a navigation experiment in the 1960s. Using five satellites orbiting the poles, the air force could observe changes in frequency that could pinpoint a submarine's location in a matter of seconds.
Today, GPS is used for mapmaking, farming, air travel, and many other commercial and military uses. Modern GPS technologies are not built to provide directions or locate your phone or tablet.