Answer:
D. removed itself from involvement in European affairs.
Step-by-step explanation:
The Monroe Doctrine was based on the statement issued by former United States President, James Monroe to Congress in 1823. The statement is centered on the foreign policies of the United States which stated that the United States will not influence the affairs of Europe, and in return, the Europeans will not influence the affairs of the whole of North and South America.
Hence, a long-term result of the Monroe Doctrine was that the United States "removed itself from involvement in European affairs."