What is the currency used in the European Union?

The currency used in the European Union is the Euro. Introduced in 1999 and adopted by many EU countries, the Euro serves as the primary currency for 19 of the 27 member states, collectively known as the Eurozone. This currency was created to facilitate easier trade and economic stability among European nations, allowing for price transparency and reducing exchange costs for businesses and travelers within the Eurozone.

The other currencies mentioned are not used by the majority of European Union nations. The Pound is primarily used in the United Kingdom, which, while previously a member of the EU, does not use the Euro. The Dollar refers mainly to the currency of the United States and a few other countries, and the Yen is the currency of Japan. Therefore, the Euro is distinctly recognized as the main currency within the framework of the European Union, making it the correct answer.