The system that evolved in Europe out of the collapse of the Roman Empire was:

Imperialism refers to the policy of extending a country's power and influence through colonization or military force. While the Roman Empire practiced imperialism, the period following its collapse did not see the continuation of such expansionist policies in Europe. Instead, the focus shifted to localized governance and land management.

Absolutism is a political doctrine where a single ruler holds total power, often justified by divine right. Although absolutism became prominent in later European history, it did not define the immediate post-Roman landscape, which was marked by decentralized power structures and local lords rather than strong centralized monarchies.

Republicanism emphasizes a system of government where representatives are elected by the citizenry. This concept was more aligned with earlier Roman governance and did not fit the fragmented political landscape of early medieval Europe, where loyalty to local lords overshadowed communal representation.

Protocapitalism refers to the early stages of capitalist development, which began to emerge much later in the Middle Ages. The immediate aftermath of the Roman Empire was marked by feudal arrangements rather than the market-driven economic systems associated with capitalism.