The European Union is/was ( )
A.
a federal entity in which the Member States have restricted their sovereign rights;
B.
established in 1957 by The Treaties of Rome;
C.
a unique economic and political union with its own currency EURO among 27 member states except the UK;
D.
a unique economic and political union with the key value of Four freedoms of movement, namely Freedom of movement for workers, Freedom to provide services, Free movement of goods, and Free movement of capital.