An economic and travel area consisting of 28 European nations is known as the ________________.

The European Union (EU) is indeed the correct answer as it represents a political and economic union of 27 European countries (after Brexit, the UK is no longer part of the EU), which promotes economic collaboration, political stability, and a single market allowing for the free movement of goods, services, people, and capital among member states.

The EU facilitates economic cooperation between its members and is an important economic area on the global stage, comprising a significant population and GDP. It also establishes regulations and standards that members must adhere to, fostering a unified economic policy.

In contrast, the Commonwealth of Nations refers to a political association of primarily former territories of the British Empire, not limited to European countries or economic integration. NAFTA (North American Free Trade Agreement), now replaced by the USMCA (United States-Mexico-Canada Agreement), specifically concerns trade between the U.S., Canada, and Mexico, and is unrelated to European nations. NATO (North Atlantic Treaty Organization) is a military alliance aimed at mutual defense, not an economic or travel area. Thus, the European Union stands out as the appropriate choice in the context of an economic and travel area among European nations.