maybe because sheep (oaia) ≠ cabbage (varza)

You should provide some context.
The original sentence is:
"I have the cabbage, you have the cauliflower." - "Eu am varza, tu ai conopida."

Did you have to choose the third word from a drop-down list? There's a problem with Duolingo, it should show in the list the correct answer and a bunch of words that don't fit because of the grammar. However, it sometimes shows words which are grammatically correct, but are just not part of the original sentence. Is that the case here?