What was the significance of the Monroe Doctrine? Olt increased American trade with Latin American countries.

Oit solved the problem of piracy in the Caribbean.

O it provided military aid to Spain to fight the British.

it opposed European involvement in the Americas.

The Monroe Doctrine opposed European involvement in the Americas.

Explanation:

The Monroe Doctrine dates from 1823 when President James Monroe introduced the idea in a State of the Union address.  Many of the former colonies in the Americas at the time were gaining independence from  Spain and Portugal as the United States had decades earlier from England.  In his address, Monroe made it clear that any attempt to reassert influence or take control of an independent state in the Americas would be viewed as an agressive move against the United States. The Monroe Doctrine was one of the fundamental principles of foreign policy for the United States and was picked up as a tenant by other presidents like Theodore Roosevelt who intervened in European dealings in Panama and Venezuela. Ronald Reagan and his administration also invoked it in how they approached El Salvador in the 1980s. The United States takes on the dominant role in the Western hemisphere under this principle.  

the answer is:

c. economic output