Which of the following best describes the prime meridian?

a. the meridian at which longitude is defined to be 0 degrees
b. the only line of latitude that is also a great circle
c. the only line of longitude that is also a great circle
d. the location of a place on earth north or south of the equator

Answer;

A. The meridian at which longitude is defined to be 0 degrees

Explanation;Longitudes are imaginary lines going from south pole to north pole. These lines are known as meridians. Zero degrees longitude is an imaginary line known as the Prime Meridian or the Greenwich meridian. The Prime meridian acts as the starting point for measuring distance both east and west around the Earth. The meridian runs through Greenwich, England and is internationally accepted as the line of 0 degrees longitude.The lines of all longitudes or meridians are great circles, unlike in the case of lines of latitude where only the equator is a great circle.

Does this your question?