Which theory warned that if one nation falls to communism, neighboring nations would fall as well?

Which theory warned that if one nation falls to communism, neighboring nations would fall as well?

• A. Containment Theory
• B. Domino Theory
• C. Brezhnev Doctrine
• D. Truman Doctrine

Answer: (B)

The idea being tested is the fear of a domino effect in which one country turning to communism could trigger neighboring nations to do the same. This warning is the Domino Theory, which argued that a single country’s shift to communism would lead to a rapid spread to its neighbors, shaping U.S. foreign policy to prevent such spread. Why this matches best: it directly describes the sequential chain reaction the theory warned about—the idea that one slide toward communism could cause a regional collapse of governments. The other concepts describe different aims or actions: Containment Theory is about preventing the spread of communism in general, not the specific cascade; the Truman Doctrine focuses on providing aid to countries resisting communism; the Brezhnev Doctrine asserts the Soviet Union’s right to intervene to keep socialism in place, not the idea of neighboring countries falling one after another.

The idea being tested is the fear of a domino effect in which one country turning to communism could trigger neighboring nations to do the same. This warning is the Domino Theory, which argued that a single country’s shift to communism would lead to a rapid spread to its neighbors, shaping U.S. foreign policy to prevent such spread.

Why this matches best: it directly describes the sequential chain reaction the theory warned about—the idea that one slide toward communism could cause a regional collapse of governments. The other concepts describe different aims or actions: Containment Theory is about preventing the spread of communism in general, not the specific cascade; the Truman Doctrine focuses on providing aid to countries resisting communism; the Brezhnev Doctrine asserts the Soviet Union’s right to intervene to keep socialism in place, not the idea of neighboring countries falling one after another.