Kennedy’s line came in a 1963 speech in West Berlin that sought to show solidarity with the “free people” of Berlin.  It was also widely seen as a speech which stood against any sense of Soviet aggression in East Germany.  Kennedy’s marked anti-communism and Berlin’s place in the Cold War are important starting points to rule out answer choices that do not indicate either of those facts.

Following the culmination of World War II, the economies of Europe were heavily ravaged by the effects of war. The Marshall Plan, implemented in 1948, was designed to assist these countries economically and re-build them to close to their pre-war strength. The intention was to prevent the Western countries from embracing Communism which was taking hold throughout, the even more impoverished, Eastern Europe.

The Contras were an anti-Communist force dedicated to overthrowing the Sandinista government of Nicaragua, led by Daniel Ortega.  The Reagan administration had attempted to fund the Contras by selling Arms to Iran, despite an Embargo on trade there since the Islamic Revolution of 1979.  The Scandal was discovered in November 1986 after Iranian elements leaked information of the arms sales.

The Kellogg-Briand pact was the brain child of United States Secretary of State Frank Kellogg in 1928. It was a treaty, signed by many nations, including the Soviet Union, which officially renounced war as a means of national policy. Although proposed by a United States’ representative, it did not gain majority support in American society and the U.S. continued to heavily invest in its military throughout peacetime. 

Several decades of American interference and militaristic action had soured relations heavily between the United States and Latin America by the time of JFKs inauguration in 1960. To combat this Kennedy proposed a ten-year plan called the Alliance for Progress, which he hoped would halt and reverse this trend. The plan called for political stabilization in the region, economic co-operation and generous American aid. Although the plan did help play a role in the growth of Latin American domestic output in the 1960s and 1970s, lack of support from later Presidents and an unwillingness on the part of many Latin American governments to agree to American proposals ultimately lead the plan to be viewed as a failure. 

The name given to the crisis that began with the Islamist students' taking of the American Embassy in Tehran, Iran, is called the Iran Hostage Crisis. 

The Nuclear Non-Proliferation Treaty was signed in 1968 by President Lyndon B. Johnson. The stated aims of the Treaty are to prevent the spread of nuclear weaponry to new countries, to co-operate on the peaceful use of nuclear technology, and to encourage the trend of gradual nuclear disarmament.

In the 1950s the United States found itself needing to fill a power vacuum in the Middle East, following the withdrawal of France and Great Britain. The threat of Soviet influence, or direct control, prompted President Eisenhower to issue a speech that would soon come to be known as the Eisenhower Doctrine. It promised economic and military aid to countries in the Middle East. As well as, assurances that the United States would provide aid and possibly troops to any sovereign nation threatened with invasion by a Communist regime. 

The Munich Pact was an agreement made between the major European powers in 1938, which allowed Germany to occupy the Sudetenland, then part of Czechoslovakia. The agreement was primarily the result of British, French, and German diplomatic maneuvering. As part of the agreement, Hitler promised to halt his desire for territorial expansion. At the time it was viewed as a successful measure to avoid war; however it quickly began to be seen as a catastrophically failed and  act of appeasement. The Pact was important for the United States, because it precipitated a series of events that would draw the United States into the conflict. Had war in Europe been declared in 1938, as opposed to 1939, the United States would have had less time to prepare, and the whole conflict might have gone differently.

The Potsdam Conference convened in occupied Germany in July and August of 1945. It was a meeting of the heads of state of the victorious powers (the Soviet Union, Great Britain, and the United States). The purpose for the Conference was to sign a series of post-war treaties, to decide how to organize war ravaged Europe and to establish order throughout the world. The United States was represented by Harry S. Truman who had very recently succeeded to the presidency, following the death of Franklin D. Roosevelt.