The quiz doesn't mention overseas territories, it mentions overseas "possessions". Just take it to mean and dependent or controlled territories anywhere in the world regardless of official status.
I would suggest adding a note to let folks know if Antarctic claims are included or not. The reason being there are a lot of conflicting and overlapping claims, some of which are not recognized (e.g. the US and Russia doesn't recognize anyones claims to Antarctica).
I feel like this should be obvious for someone who's been here for a while, but Antarctic claims are never included in this type of quiz, for the simple reason that no part of Antarctica belongs to any country. They are not overseas territories or possessions.
United Kingdom: Cyprus base area => Pitcairn.
United States: Virgin Islands => Guam
Norway: Svalbard => Antarctic island (unlabeled on Google maps)
Tromelin to Clipperton is 18 Mm
Kerguelen to Clipperton is 16 Mm
And Bonaire, Saba and St Eustatius are special municipalities.
it depends on if QM chose to keep Antarctic Possesions.