Identify the policies of the Monroe Doctrine. declared that European nations
must not colonize nations in the
Western Hemisphere
stated that the United States
wouldn't interfere with European
affairs
declared that European nations
could no longer trade with the
United States and other nations
in the Western Hemisphere
stated that the United States would
take military action against any
European effort to colonize nations
in the Western Hemisphere

You... answered your own question.

Explanation:

If you are trying to verify, yes! It, in short terms, stated that Europe had to leave South America alone, and based on the political situation, worldwide (especially in relation to Britain and the recent wars) no one had the power to challenge it until it was so ingrained in law that the desire was no longer worth it.  

the second significant cause of the great migration was the desire of black southerners to escape segregation, known euphemistically as jim crow. rural african american southerners believed that segregation - and racism and prejudice against blacks - was significantly less intense in the north.