What Important Concept Was Put in Place with the Monroe

What important concept was put in place with the Monroe Doctrine?

A) Foreign countries were required to stay out of North and South America.
B) The European countries that had a presence in the Americas were forced to give up their colonies to the United States.
C) The U.S. had a right to interfere in European politics.
D) The U.S. would welcome European involvement to protect its interests in Latin America.