Final answer:
The currency that integrates the EU's monetary systems is the euro.
It was adopted by most EU members since its introduction in 1999, replacing many national currencies and centralizing monetary policy under the European Central Bank.
Step-by-step explanation:
The currency used to integrate the monetary systems of the European Union (EU) is called the euro (C). The euro was introduced in 1999 and has been adopted by most EU members.
Some countries within the EU, such as Great Britain, have decided to keep their traditional currencies; for example, the UK continues to use the pound sterling. The euro has replaced many former currencies like the German Mark, French Franc, Italian Lira, among others.
Despite the benefits of having a common currency, there are also challenges because adopting the euro means that nations relinquish control over domestic monetary policy to the European Central Bank.
The currency used to integrate the monetary systems of the European Union (EU) is called the euro. The euro was introduced in 1999 and is currently used by most EU countries as their national currency.
However, not all EU countries have adopted the euro, as some, like the United Kingdom, have chosen to retain their own currencies, such as the pound sterling.