Comment by rob74
There are words that can have several Artikel, sometimes depending on regional differences (e.g. Austrians have different preferences than Germans), sometimes because of multiple meanings of a word. In that case, I would expect the game to accept all valid answers. But I got the impression that all words were singular, so "der" would be the only valid option for "Ausländer". I had a similar issue with "Geschwister", where I picked "das" (correct according to https://www.duden.de/rechtschreibung/Geschwister), but the game expected "die" (which IMHO only makes sense for the plural form). Looks like it needs a bit more QA :)
> I had a similar issue with "Geschwister", where I picked "das" (correct according to https://www.duden.de/rechtschreibung/Geschwister)
The actual correct singular form of "[die (since plural)] Geschwister" is "das Geschwist" - a word that is rather obscure even for many native German speakers.