Answer:
b. declared the Americas off-limits for further European colonization.
Explanation:
John Monroe was an American diplomat, lawyer and statesman who was elected as the fifth president of the United States of America, he served from 1817 to 1825. President Monroe was born on the 28th of April, 1758 in Monroe Hall, Virginia, United States of America.
After the War of 1812, the United States of America and Great Britain had series of improved relationships with one another. These mutual relationships gave rise to the signing of the 1817 Rush-Bagot Pact and Convention of 1818 which played a significant role in the resolution of longstanding boundary disputes with respect to the 1783 Treaty of Paris.
Under President James Monroe, the 49th parallel was set as the boundary between the United States and Canada by Convention of 1818, which was signed on the 20th of October, 1818 in London, United Kingdom.
On the 22nd of December, 1823, President Monroe published the "Monroe Doctrine" in which European Colonialism in America was strongly prohibited and as such the Western Hemisphere was forbidden to the European powers.
Hence, the Monroe Doctrine declared the Americas off-limits for further European colonization.
