Final answer:
The decision-making process that requires unanimous consent from all members before action can be taken describes a confederal government, which is characterized by member states retaining substantial power and needing to agree for central action.
Step-by-step explanation:
The statement "All members must have unanimous consent (complete agreement) before any action may be taken" refers to the decision-making process in a confederal type of government. In a confederal system, the member states retain considerable power and are required to agree before the central authority can act. This is different from a unitary system, where the central government has the most power and can create laws without requiring unanimous consent from subnational units. In a federal system, there is a mix of shared power between the central government and subnational entities, with a constitution typically requiring a supermajority for amendments, but not unanimity for regular legislation.