Explanation:
Athough initially disregarded by the great powers of Europe, the Monroe Doctrine became a mainstay of U.S. foreign policy . In 1823 U.S. President James monroe proclaimed the U.S. protector of the western Hemispere by forbidding European powers from colonizing additional territories in the Americas.
Under the feudal system the king owned the land, which he then divided up among his nobles in exchange for payment (feuds)
The Columbian Exchange greatly affected almost every society on earth, bringing destructive diseases that depopulated many cultures, and also circulating a wide variety of new crops and livestock that, in the long term, increased rather than diminished the world human population:)