My answer was "Have you red paint". It was marked wrong noting that "got" was missing. My English teaching parents would scold me if I asked "Have you 'got' red paint?" "Do you have red paint?" or "Have you red paint?" seem more correct.
It's a question, so I'm guessing: Ni har röd färg. (You (pl.) have red paint), when you switch the subject and the verb, becomes Har ni röd färg? (Have you [got] red paint?/Do you have red paint?) But I'm puzzled by this because I think I saw a lesson called "questions" later on in the tree, so I'm not sure whether this type of sentence is prematurely here?