In that case: De spør spørsmål. (Not spørrer). But it is a bit weird. It will be like saying I'm going to run for a run (when you are actually just going to exercise and do it by running).
To ask a question = å stille et spørsmål = å spørre (no need to say it's a question as it's already there in the verb itself).
In some dialects it would not just sound odd, but childish, to say "De spør spørsmål". A construction like "De spør om..." (translated: "They ask if..." would fit in a lot of situations. I think grydolva is very much to the point here. When you use the verb "å spørre" it is understood that you talk about a question.
I know, I lived in Troms for nearly 10 years and interacted a lot with people from Nordland, too. Since Duolingo doesn't seem intent on teaching any of the structures most often found in spoken Norwegian, I still think it is good advice to learn the most standard expressions first.