The purpose of the Roosevelt Corollary, announced by President Theodore Roosevelt in 1904, was primarily to discourage European nations from intervening in Latin America. It was a significant modification of the Monroe Doctrine and asserted that the United States would act as a police power in the Western Hemisphere, intervening in Latin American countries to maintain stability and order, thus preventing European powers from using debt crises as a pretext for military intervention.
Therefore, the correct answer is: To discourage European nations from colonizing Latin America.