What term describes the idea that if one country falls to communism, neighboring countries will also fall?

• A. Containment Theory
• B. Domino Theory
• C. Threshold Theory
• D. Spiral Model

Answer: (B)

The idea being tested is the domino effect in geopolitics: when one country falls to communism, neighboring states are believed to be likely to follow. This concept describes a chain reaction across borders, which is why it’s tied closely to Cold War anxieties about regional spreads of ideology and influence.

This is the best answer because it explicitly names the notion of a cascading fall from one country to its neighbors, capturing the spatial, contagion-like logic the question asks about. In contrast:

• Containment involves preventing the spread of communism, not asserting that it will automatically cause neighboring countries to fall.

• Threshold theory centers on tipping points in adoption among populations, not a geographic cascade of political regimes.

• Spiral model refers to cyclical escalation in conflict or policy dynamics, not a simple neighboring-country contagion.

So, the domino theory best fits the described idea.