Answer:
d. European Union
Step-by-step explanation:
Initially, Belgium, France, Italy, Luxembourg, the Netherlands, and West Germany signed the Treaty of Rome back in 1957 creating the (EEC).
They eventually continued to form alliances leading to economic integration, cooperation and aid & development.
The European Union formed as a continuation of the works of the European Economic Community (EEC).
The European Union began as a customs union, with time it encouraged economic and regional integration. By 1993, the members expanded the scope and the number of states and formed the European Union incorporating the former EEC.
This created the biggest market by eliminating the trade barriers and setting a common policy on foreign trade-
The Treaty of Rome in 1957 was a key step in bringing Europe into the world stage again as an economic bloc-
Eventually, freedom of market enabled later conditions for establishing a common migration policy towards the reallocation of workers and further sectors.