"¿Cuál es la nacionalidad de tus abuelos?"
Translation:What's your grandparents' nationality?
I think they are just dictionary hints and word translations and you have to add the punctuations yourself as you do with "nationality?" E.g "What is the nationality of your grandparents?" is also correct.
There we no words in the word bank for building What is the nationality of your grandparents?
this is an old Duolingo bug, it’s been around for years. somehow it cannot deal with words ending with an apostrophe.
Can someone please explain to me why ' cuál ' is translated into 'what' and not 'which' ?
'cuál' can be either. In this case, we don't normally say 'Which is your Grandparents' nationality' in English. We normally say 'What' instead so that is what this translates to.
Now, (and this is being somewhat overly strict here) if you think about it it is actually English that is odd in this case. The word 'which' implies a choice from a list so by that logic 'which' should be the one used here as the list of nationalities is finite and can be selected from. Language rules aren't always so clear cut though.
Ditto LeeBrowns1's comment. The English sentence is grammatically wrong, making it confusing.