I wondered the same. It seems like a mistake, but the "mistake" is on all three choices.

Not only that, the one I chose was correct "Де вони їдять ввечері", but the translation in Discuss shows a completely different option: "Де вони їдять увечері?"

I mean, it's not even saying "here is another way", it's just stating it as if it was in one of the options but it wasn't.