The fall of Rome was a complex event influenced by multiple factors rather than a single primary reason. However, if one had to choose a primary reason from the options provided, internal corruption is often emphasized by historians as a significant factor.
While invasions by the Huns and other barbarian groups contributed to the decline, and economic collapse also played a critical role, internal corruption weakened the political structure of the Roman Empire, leading to ineffective governance, loss of public trust, and an inability to respond effectively to external threats.
Thus, while all these factors were interconnected and important, internal corruption is frequently highlighted as a key reason for the fall of Rome.