Eratosthenes Was the First Person to Accurately Estimate the Size

Multiple Choice

Eratosthenes was the first person to accurately estimate the size of the Earth.He accomplished this feat by

A) sailing around the world and estimating his average rate of travel.
B) comparing the length of an Earth day with the distance between the Earth and the Sun.
C) measuring the severity of the greatest earthquakes.
D) observing shadows cast simultaneously at two different cities that were separated by a known distance.