What term is used to measure angular differences east and west of the Prime Meridian?

The term used to measure angular differences east and west of the Prime Meridian is "meridians." Meridians are the imaginary lines that run from the North Pole to the South Pole, perpendicular to the lines of latitude (parallels) which measure angular distances north and south of the Equator.

Each meridian represents a specific angle measured in degrees, with the Prime Meridian serving as the reference point at 0 degrees. As you move east or west along the globe, the degrees increase up to 180 degrees in either direction. This system is crucial for navigation and geographic orientation, allowing for precise location identification on the Earth’s surface.

The other options pertain to different concepts: circles refer to shapes without specific geographic significance, parallels define lines of latitude which measure north and south, and coordinates refer to a system used to define a precise location using both latitude and longitude, encompassing both meridians and parallels, rather than specifically addressing angular differences east and west.