The main idea is extending containment to the Middle East by promising economic and military aid to nations resisting communism. In 1957, the Eisenhower Doctrine did exactly that: it pledged U.S. economic and military assistance to Middle Eastern countries facing communist pressure and stated that the United States would use force if necessary to defend them. This reflected a shift in Cold War strategy to guard critical oil resources and prevent Soviet influence from spreading into a volatile region after events like the Suez Crisis. Think of how this differs from broader but older efforts: the Truman Doctrine focused on preventing communism from taking hold in Europe, especially Greece and Turkey, and the Marshall Plan focused on rebuilding Western Europe after World War II. Containment, meanwhile, is the overarching strategy of keeping communism from expanding, not a single policy aimed at the Middle East. The Eisenhower Doctrine is the specific regional application of that containment idea, defining a clear commitment to aid and potential intervention in the Middle East when faced with communist threats.

Douglas MacArthur served as the commander of UN forces in Korea, holding the role of Supreme Commander for the United Nations Command. When North Korea invaded South Korea in 1950, his leadership guided the early response: he helped organize the defense at the Pusan Perimeter and then crafted the bold Inchon landing, which outflanked the North Koreans, recaptured Seoul, and allowed UN forces to reverse the invasion. This sequence—stubborn defense followed by a decisive counteroffensive—defines why he is remembered as the leader who repelled the North Korean invasion. He remained the top commander until 1951, when he was relieved by President Truman over strategic disagreements. The other figures were prominent in other contexts (World War II or different roles) and did not lead UN forces in Korea.

The scale of the Interstate system when it was established was set by law at about 41,000 miles. The Federal-Aid Highway Act of 1956 authorized roughly 41,000 miles of Interstate highways to knit the country together and improve defense mobility. That planned length—around 41,000 miles—became the standard figure cited in history and official records, so it’s the best match among the options. Shorter figures like 25,000 or 18,000 miles are beneath the authorized total, while 60,000 miles is more than what was authorized and what the system ultimately reached.

Sit-ins and nonviolent protests were driven by a network of groups that emphasized direct action and nonviolent discipline, with student-led energy at the forefront. The organization known for coordinating and leading these campaigns, while working closely with veteran groups like CORE, was the Student Nonviolent Coordinating Committee. SNCC organized the famous Greensboro sit-ins and spurred similar actions across the South, uniting students from colleges with broader civil rights networks and applying nonviolence as its core tactic. This emphasis on student-led direct action and collaboration with CORE makes SNCC the best fit. The other groups played crucial roles in different aspects of the movement: the NAACP focused more on legal strategies and court challenges; the SCLC organized large-scale, church-based nonviolent protests led by veteran leaders like MLK; CORE pioneered nonviolent direct action, including early sit-ins, but SNCC is the one most closely associated with leading student-driven sit-in campaigns and sustaining nonviolent protest across multiple campaigns in the 1960s.