Which of the Following Is True Regarding the Prime Meridian

Which of the following is true regarding the prime meridian?

A) The prime meridian passes through the Royal Observatory at Greenwich,England.
B) While latitude can be represented as both degrees,minutes and seconds and decimal degrees,longitude is always represented using decimal degrees.
C) International agreement regarding the location of the prime meridian was not resolved until the 1980s when a treaty was completed.
D) The key to measuring angular distances east and west of the prime meridian was the development of accurate compasses.
E) The prime meridian is a small circle.