How Did the Greeks Estimate the Size of the Earth

Multiple Choice

How did the Greeks estimate the size of the earth?

A) They didn't; everyone thought the world was flat until Columbus' time.
B) They measured the angle of the sun above the horizon at midday in two places with different latitude and used the angle to estimate the circumference of the earth.
C) They used the height of sailing ships as they sailed over the horizon to estimate curvature of the earth,which allowed estimation of the size of the earth.
D) They measured the altitude of mountains in Greece,then used the distance they were lost from sight to estimate the curvature of the earth,which allowed estimation of the size of the earth.