"That is the woman whose husband is a farmer."
Translation:Das ist die Frau, deren Mann Bauer ist.
It depends on the antecedent of the main clause:
masc.: Der Mann, dessen Bruder / Frau / Haus...
femin.: Die Katze, deren Besitzer / Beute / Futter...
neutr.: Das Haus, dessen Anstrich / Farbe / Anwesen...
plural: Die Männer / Frauen / Kinder, deren Tisch / Hose / Spielzeug...
It does not matter in which case the antecedent is in. I've used nominative in my examples, but one could also have them in:
genitive: Das Haus der Frau, deren Bruder... (Frau = fem.)
dative: Es gehört dem Mann, dessen Frau... (Mann = masc.)
accusative: Sahst du das Haus, dessen Fassade... (Haus = neutr.)
I wrote: "Das ist die Frau, deren Mann Farmer ist" (copy and paste) and that was not accepted.
The course has really problems with the translation of "farmer". It is only allowing to translate this word with "Bauer". That stands in contradiction with the online dictionaries:
You have forgotten to write: nominative case singular demands "is", because nominative case plural demands "sind". You should not forget the other possibilities of the conjugation for "sein":
Singular: ich bin / du bist / er, sie, es ist
Plural: wir sind/ ihr seid / sie sind. (;
Nominative case is required with "ist"
I've just reached 180 days yesterday and this has never been a rule. I'm not saying you're wrong, but why is this news to me?? Day 1 teaches about the subject carrying the nominative. The woman is clearly the subject of the sentence, so we're taught since day 1 that whatever else comes is an object. I've now got to unlearn something I've been doing for 6 months...