The "Natural" Baselines Which Serves as a Baselines to Measure

The "natural" baselines which serves as a baselines to measure longitude (such as the Equator which is used as a baselines for latitude) ____________ .

A) is the International Date Line
B) is the Prime Meridian
C) runs near London, England
D) is at the same latitude as the Equator
E) does not exist