A loose union of independent states, that unite for a common purpose (such as defense) is a - Federal system Constitutional government Confederation Unitary system

The correct answer is Confederation.<br /><br />A confederation is a loose union of independent states that unite for a common purpose, such as defense. In a confederation, the central government has limited powers, and the individual states retain a high degree of sovereignty and independence. The central government is typically responsible for coordinating and coordinating the actions of the member states, but it does not have the authority to enforce its decisions directly on the states or their citizens.<br /><br />In contrast, a federal system is a system of government in which power is divided between a central government and subnational entities (such as states or provinces), each with their own powers and responsibilities. A constitutional government is a system of government in which the powers of the government are limited by a constitution, which sets out the rights and responsibilities of the government and the rights of the citizens. A unitary system is a system of government in which power is concentrated in a central government, with little or no power granted to subnational entities.