Belgium, along with France, (West) Germany, Italy, the Netherlands and Luxembourg — the "Inner Six" — was a founding member of which organisation established in 1957, a forerunner of today's EU?

The correct answer is the European Economic Community (EEC). The EEC represented a deeper, more integration-oriented commitment than earlier postwar cooperative bodies and eventually evolved, through subsequent treaties, into today's European Union, making it the direct institutional ancestor of the EU's economic and political structures. The distractor 'European Free Trade Association (EFTA)' is incorrect because EFTA was actually founded in 1960 by a rival group of European states — including the United Kingdom, Norway, and Switzerland — that deliberately chose a looser free-trade arrangement instead of joining the more integrationist EEC. 'Council of Europe' is wrong because it is an older, broader human-rights and democracy-focused body founded in 1949, unrelated to economic union and encompassing many more member states than the Inner Six. 'OECD' is incorrect because the Organisation for Economic Co-operation and Development, though it also emerged from postwar European cooperation, functions as a global economic policy forum rather than a customs union created specifically by the six named states. A common exam confusion arises when candidates conflate the EEC with EFTA simply because both involve European economic cooperation; the key distinguishing factor is that the EEC's six founders pursued full economic and eventual political integration, while EFTA's members preferred trade liberalisation without ceding sovereignty. The revision takeaway: the Inner Six founded the EEC via the 1957 Treaty of Rome, the direct organisational forerunner of the modern EU, and this must not be confused with EFTA, the Council of Europe, or the OECD, each of which serves a distinct purpose and membership.