The correct answer for this question is "d. he was the first to propose the idea that the earth was round." All of the following are true statements about Christopher Columbus EXCEPT he was the first to propose the idea that the earth was round.<span> </span>
The mongol empire fell for many reasons including poor leadership following the death of Kublai Khan The rulers spent money unwisely making them raze taxes which in turn led to riots throughout the mongol empire. This led to the empire to getting smaller and smaller .The empire was also in so much debt and this led to riots and fall of the empire
They didn't create warfare nor spears. They created harpoons, but not spears. Plus warfare was going on before them, so we can easily exit that one out as well. Then the compass. They didn't create that either, but they did create, The wheel, the plow, metallurgy, and cuneiform.