How did the geographic setting of north america- including its relation to asia, europe, and africa- affect its subsequent history?

The American continent is geographically inaccessible and secluded, separated by two oceans from any other countries.  

This made colonization (or invading a country) of North America which possibly only through a sea. That removed and eradicated nations with large armies as threats. The only power that could influence North America was a nation with a powerful and tough navy, like England’s.  

To our north countries like, Canada was resolved by the French, who were our alliances. To the south was Mexico, South America, and Central America.

Thus, at the start, North America had a geographic superiority against any conquering force: distance across an ocean. However, the United States of America can grow and establish their own identities separately from their parent and other countries.

no options provided, here,but the answer to this question is often: a historian cites a japanese newspaper article published a year after the end of world war ii in order to draw conclusions about the effect of the war on the japanese economy.

clearly from the answer, the historian alludes to historical sources,and records to aid in analyzing and drawing conclusion on the effect of the war on the economy of japan.