The correct answer is option 2: APEC. India is not a member of the Asia-Pacific Economic Cooperation (APEC) organization. APEC is an intergovernmental forum that promotes economic cooperation and trade among countries in the Asia-Pacific region. It consists of 21 member economies, including countries such as the United States, China, Japan, Australia, and Canada.

Option 1: ADB (Asian Development Bank) - India is a member of the Asian Development Bank, which is a regional development bank that provides financial assistance and support for infrastructure and sustainable development projects in Asia and the Pacific region.

Option 3: Antarctic Treaty - India is a member of the Antarctic Treaty System. The Antarctic Treaty is an international agreement that regulates human activity in Antarctica for peaceful purposes and preserves the continent for scientific research and environmental protection.

Option 4: Colombo Plan - India is a member of the Colombo Plan. The Colombo Plan is a regional intergovernmental organization that focuses on economic and social development in the Asia-Pacific region. It promotes cooperation and collaboration among member countries in areas such as trade, investment, and human resource development.