The correct answer is number 3. Intervene in Latin America to prevent European interference.
President Theodore Roosevelt strengthened the Monroe Doctrine by establishing the policy that the United States would intervene in Latin America to prevent European interference.
"Roosevelt Corollary" was the Roosevelt way to act in Latin American in the case of any European intromission in the region. In the case of any wrongdoings by a Latin American nation such as riots, rebellions, or large debts, The United States could intervene to solve the issue. This meant that it would be the US that played the new role of "police patrolling" Latin American countries to avoid European intervention, as was the case of the Dominican Republic in 1905.