Which is the correct explanation for 120°w longitude?
a. all positions along a circle that runs perpendicular to the equator and 120° west of the prime meridian
b. all positions along a circle that runs perpendicular to the equator and 120° east of the prime meridian
c. all positions along a circle that runs parallel to the prime meridian and 120° east of the equator
d. all positions along a circle that runs perpendicular to the prime meridian and 120° west of the equator