It means "Les chats peuvent voir la nuit.", it's different. Being in the dark doesn't mean it's night, you could be in a room with no lights.
If we do a literal translation, it should be "The cats can see in the black.". I don't believe we want to do that.
I'd say this goes with duolingo's theme of actually translating what's written, instead of what is understood. I wrote the same thing and it was wrong, though I can see why based on the prompt.
I think it could also mean "Cats can in the dark" as cats in general and not THE cats as some specific cats.
Yes, it does also mean that. That's what I wrote and it was accepted