The major achievement of the Economic Community of West African States (ECOWAS) is that it has

Step 1: Analyze the question The question asks for the major achievement of ECOWAS, which was founded in 1975 (Treaty of Lagos) to promote economic integration among West African states.

Step 2: Explain the concept ECOWAS aims to remove trade barriers, promote free movement of goods, services, and people, and build a larger regional market. Its major gains come from trade liberalisation (the ECOWAS Trade Liberalisation Scheme) and the free movement protocol.

Step 3: Evaluate each option

• A. Made capital more mobile: Capital mobility is a goal, but it has not been the standout achievement. Capital controls and differing financial systems still limit it.
• B. Common currency: This has not been achieved. The planned "Eco" currency has been repeatedly delayed. Only the francophone members use the CFA franc, and that existed separately under WAEMU/UEMOA.
• C. Increased allegiance to former colonial masters: This is the opposite of ECOWAS's purpose, which is to promote self-reliance and regional integration.
• D. Widened the market for goods produced: By reducing tariffs and trade restrictions among 15 member countries, ECOWAS gives producers access to a much larger market than any single national market. This is its most tangible achievement.

Step 4: Answer The correct option is D. widened the market for goods produced.

Tip: For questions on regional economic groups (ECOWAS, EU, etc.), remember that the widening of markets is the classic benefit of integration. Be wary of options like "common currency" unless the question is clearly about a group that has one, like the Eurozone.