Correct option is C
The Economic and Monetary Union (EMU) created in 1992 by the Maastricht Treaty was famously incomplete. 1 January 1999, saw the start of Stage Three of Economic and Monetary Union (EMU), with the introduction of the euro and a single monetary policy for the euro area.
The European Monetary Union, which established the common monetary policy and currency (the euro) for the Eurozone countries, was officially created in 1999.