The Last Country to Occupy Each Oceanian Country

Occupy implies hostile troops, however your approach here is often based on political control rather than military occupation. The last troops to have occupied many of these Oceanian countries were either Japanese or American during WW2, yet Japan isn't the answer for anything in the quiz. I think it should be.

Depends on which islands. Some were still in Japanese control when Japan surrendered. The US marines did the majority of the invasions of Japanese controlled Pacific islands in the latter stages of WW2, Australian/NZ troops were deployed in New Guinea and Indonesia rather than the outer Pacific islands. The US island hopping campaign avoided the heavily fortified islands where possible because the main aim was to secure bases as close as possible to the main islands of Japan, and so not all occupied Pacific islands were brought under control by the allies at the time when Japan surrendered. Japan still controlled a few parts of northern New Guinea at the surrender date for instance also. It's a bit complicated :)

The dates do make it cleaner. For the reason in my first comment, I'd suggest "control" would be a better choice than "occupy".