The distance in degrees east or west of the prime meridian is called
a latitude
b axis
c equator
d longitude

The distance in degrees east or west of the prime meridian is called longitude. The Prime Meridian was established to be the zero point from which other longitudinal points would be measured from. Latitude is the measure of points on the globe based upon their location from the equator based upon a north/south direction. The equator is the center point of the globe in the scale of latitude and is an artificial line that runs around the globe dividing the globe into the northern and southern hemispheres.