What is the significance of the Prime Meridian?

The Prime Meridian is significant because it serves as the zero-degree longitude line. This line runs from the North Pole to the South Pole, dividing the Earth into the Eastern and Western Hemispheres. It is essential for global navigation as it provides a reference point for determining the longitude of locations around the world. All longitudinal measurements are taken in degrees either east or west from this line. Understanding the significance of the Prime Meridian is crucial for navigators and cartographers since it helps in accurately plotting positions on a map or chart, as well as in navigation calculations necessary for maritime and aerial navigation.

In contrast, the other options refer to concepts that do not accurately represent the Prime Meridian's purpose or functionality in navigation and mapping practices. Latitude lines, altimeter settings, and chart symbology each serve distinct purposes, but they do not pertain to the role of the Prime Meridian as a reference for longitude.