The us government was very involved in latin america during the cold war, often in an attempt to
a. establish agricultural trade, especially for tropical fruit such as bananas
b. rebuild the panama canal and increase shipping
c. promote english as the most common language in the region
d. stop the spread of communism in the region

D. stop the spread of communism in the region

After 1959 toward Soviet communism alienated the United States. An attempted invasion failed, and at the peak of the Cold War in 1962, the Cuban Missile Crisis threatened major war as the Soviet Union installed nuclear weapons in Cuba to defend it from an American invasion. There was no invasion, but the United States imposed an economic boycott on Cuba that remains in effect, as well as a break of diplomatic relations that lasted until 2015. The US also saw the rise of left-wing governments in central America as a threat, and in some cases, overthrew democratically elected governments perceived at the time as becoming left-wing or unfriendly to U.S. interests.

Examples include the 1954 Guatemalan coup d'état, the 1964 Brazilian coup d'état, the 1973 Chilean coup d'état and the support of the Contra rebels in Nicaragua. In 1980s, the United States gave strong support to anti-Communist forces in Latin America. The fall of Soviet communism largely ended in 1989–91 the communist threat. By 2015 relations remain tense between United States and Venezuela. Large-scale Mexican immigration grew the late twentieth century, so that over 10 million undocumented immigrants lived in the United States, sending money back home and asking whether they or their children could get US citizenship. Furthermore large-scale immigration came from smaller countries such as Haiti and the Dominican Republic.

Democracy and darwinism would be my answer.