The correct answer is: B. Monroe told European countries to stay out of the Americas.
The Monroe Doctrine said specifically that the United States would not permit European countries to start new colonies or to get in the way of independent countries in the continents of North America and South America; in return, the United States would not get in the way of existing European colonies nor take part in conflicts between European countries.
The main reason for proclaiming this doctrine was, that many countries in South America had just obtained their independence from European domains, such as Spain and Portugal. At the same time with the loss or defeat of Napoleon in Europe, James Madison, fourth President of he United States, was afraid that European nations would once again try to set up their power in the Americas. James Madison wanted to let Europe know that the United States would not permit the European monarchies to recover their power in the Americas.
President James Monroe, fifth President of the United States, proclaimed that the Old World and the New World had different systems and that they must remain visible domains. The United States was also concerned about Russia's territorial intentions in the northwest coast of North America.