Which of the following is NOT a member of ASEAN?

Concept: ASEAN (the Association of Southeast Asian Nations) is a regional intergovernmental organisation of Southeast Asian states, founded on 8 August 1967 by the Bangkok Declaration. Its membership is a fixed, defined list of Southeast Asian countries only — a country outside the Southeast Asian geographic and political grouping cannot be an ASEAN member, no matter its other international affiliations.

Application: At the time this question was framed, ASEAN's membership consisted of these Southeast Asian states:

• Indonesia, Malaysia, Philippines, Singapore, Thailand — the five founding members (1967)

• Brunei (1984), Vietnam (1995), Laos and Myanmar (1997), Cambodia (1999) — later members

ASEAN's membership subsequently expanded to eleven states when Timor-Leste acceded in October 2025 — this later addition does not change the analysis below, since Fiji has never appeared on the ASEAN membership list at any point.

Checking each offered option against this list: Vietnam, Singapore, and Cambodia all appear in it, so each of them IS an ASEAN member. Fiji does not appear anywhere in it — Fiji is a Melanesian island nation in the South Pacific Ocean, geographically and politically outside Southeast Asia, and it has never held ASEAN membership.

Cross-check: Fiji's own regional affiliations confirm this — it is a member of the Pacific Islands Forum and the Melanesian Spearhead Group, groupings for Pacific Island states, not Southeast Asian ones. This independently confirms Fiji is the one option that is NOT an ASEAN member.