The order in which the above happened was:
Form the formation of the European Coal & Steel Community, there were talks of a common market in Europe and these were given a boost with the Treaty of Rome.
Other nations then joined over time until the EC officially became the EU. The British however, decided to leave the EU and did so in the year 2020.
Find out more on the European Union at https://brainly.com/question/13929900.