Which country is not part of the Indo-Pacific Quad grouping?

The correct answer is D, Indonesia. The Quadrilateral Security Dialogue, or Quad, has four members — India, the United States, Japan and Australia — and Indonesia is not one of them. The grouping grew out of the coordination between these four navies after the Indian Ocean tsunami of 2004, was set up as a dialogue in 2007, lapsed for a decade and was revived in 2017. It is an informal strategic forum rather than a treaty alliance with a standing army, and it works on maritime security, vaccines, critical and emerging technology, climate action and infrastructure across the Indo-Pacific. The Malabar naval exercise, which began as an India–United States drill, now brings all four Quad navies together. Options A, B and C are wrong because the United States, India and Japan are all founder members of the Quad. Indonesia is instead a founder member of ASEAN and a G20 member, and it works with India through forums such as the East Asia Summit and IORA. Exam tip: Quad = India, US, Japan, Australia; Malabar is the exercise of these four navies.