C) Roosevelt was concerned European countries would take action if the Dominican Republic failed to pay its debts.
The Corollary was a United State policy toward Latin America, that allowed the U.S. to intervene in conflicts between European countries and Latin American ones.
In 1904, the Dominican Republic was in serious trouble with France, Italy, and Germany because it wasn't able to pay its large debts. Roosevelt was concerned European countries would take action, and in 1905, he agreed with the Dominican Republic to supervised its debt repayment, enacted the Corollary and intervened in the matter. The United States took over the D.R. and seized its customs houses until the situation was stabilized.