"Ils ont des pommes de terre et du pain."
Translation:They have potatoes and bread.
It may be worth pointing out that using "avoir" here (for "have") only means that they possess it. "Have" is also used in the sense of consuming food or drink but that is a different verb (prendre), e.g., ils prennent des pommes de terre et du pain" = they are having potatoes and bread.
It didn't accept the form "They've got", which, I think, is perfectly acceptable and current UK English.
I think DL does allow it in some other exercises.
I have reported it.
Update: Just been informed (only a few hours later) that they have accepted my suggestion and “They've got potatoes and bread.” should now be accepted.