How was the mayan economy similar to the economy of ancient river civilizations? a) the maya traded locally available materials for materials from other regions.
b) the maya developed a currency for purchasing materials from other regions.
c) the maya used jade, obsidian, and quetzal feathers to obtain materials.
d) the maya did not trade or purchase materials because the economy was dependent on the ruler.

the american revolution led to the creation of a democratic republic,is the correct answer;

isaac newton first proposed that earth was not perfectly round. instead, he suggested it was an oblate spheroid—a sphere that is squashed at its poles and swollen at the equator.

the idea of the earth being a flat disc is also inconsistent with the fact that a given lunar eclipse is only visible from half of the earth at a time. the only shape that casts a round shadow no matter which direction it is pointed is a sphere, and the ancient greeks deduced that this must mean the earth is spherical.