What describes a nation-state?

A nation-state is defined as a political entity where the boundaries of a state align with a specific cultural or ethnic group, which has developed a shared identity and a sense of nationalism. This relationship between the state and the ethnic group means that the territory of the state corresponds closely to the homeland of the nationality it represents. This concept emphasizes not only geographic boundaries but also the cultural and social unity that fosters national identity among people sharing common language, traditions, and heritage.

In contrast, other options present ideas that do not capture the essence of a nation-state. For instance, a state governed solely by international treaties and laws lacks the sovereignty often associated with a true nation-state, which exercises its own governance over a defined territory. A political entity with no defined territory contradicts the foundational aspect of a nation-state, which is its territorial integrity. Lastly, focusing on economic unions and trade agreements does not encompass the cultural and nationalistic elements that define a nation-state, as it emphasizes economic relationships rather than the cohesive identity shared by a population within a defined territory.