Indonesia is the only Southeast Asian country that is a member of which major grouping of the world's largest economies?

The correct answer is G20, the Group of Twenty, an international forum comprising 19 individual countries plus the European Union and the African Union, representing the world's major developed and developing economies and accounting for a substantial share of global GDP, trade, and population. Indonesia is the sole ASEAN member state among the G20's country participants, a position it holds due to its status as Southeast Asia's largest economy by GDP and the world's fourth most populous nation. Indonesia's G20 membership reflects its growing global economic weight, and the country notably hosted the G20 Summit in Bali in 2022, further cementing its role in international economic diplomacy. G7 is incorrect because it is a smaller, more exclusive grouping of seven highly industrialised nations, namely the United States, United Kingdom, Canada, France, Germany, Italy, and Japan, none of which are Southeast Asian, and Indonesia has never been a G7 member. BRICS is incorrect for this question's context because, while BRICS has undergone expansion in recent years to include new members, Indonesia's primary and long-standing distinguishing multilateral economic membership tested in this context is the G20, and BRICS membership does not carry the same 'only ASEAN member' distinction being tested here. OECD is incorrect because it is a separate organisation of mostly developed, high-income economies focused on policy coordination, and Indonesia is not a full OECD member, though it has engaged in accession-related dialogue. A common exam confusion is mixing up G20 with G7 due to similar naming, or assuming ASEAN membership automatically implies G20 membership for all ten member states, which is false since Indonesia alone carries this distinction. Revision takeaway: Indonesia is ASEAN's sole G20 member, reflecting its position as the region's largest economy.