I too thought 'this is', as in English you could say 'this is the cats food' or 'that is the cats food'. depending of the location of the food. Then of course we could clarify by saying 'this here is' or 'that there is', but rarely would we say it that way unless there was two different types of food :P
I think it's fairly natural to say "It is..." in reply to a question, e.g. "What's in the blue bowl?" "It is the cats' food."
It really works with any sort of follow-up phrase, too, e.g. "You mustn't eat that, it's the cats' food!"
It does sound rather strange as a stand-alone sentence, but without any context it probably sounds strange in Swedish too.
There's a technical problem with putting hints on words that contain apostrophes which may be causing this, but there may be something else going on too. I'd actually appreciate having a look at that screenshot. If you could upload it to some image service and post a link here, it would be great.
Depends on how you form the sentence. If you have it as "the cats' food" it's just food but if you put the food at the beginning you would have to say "the food of the cats" because "this is food of the cats" wouldn't be proper english. Of course mat is in the indefinite form though.
In English, or in Swedish?
In Swedish, cat's (in the sense of "belongs to a single cat") would be either katts (indefinite) or kattens (definite), while cats' (in the sense of "belongs to multiple cats") would be either katters (indefinite) or katternas (definite).
In English, it's based entirely on the location of the apostrophe. Cat's is singular, while Cats' is plural.
Because "mat" doesn't mean "meal", it only means "food". Most of the time, we wouldn't really NEED to make a distinction between meal and food, but when you think about it, there is a difference. For example, "I've just finished buying the food." - This would suggest that you bought a whole lot of food, maybe for a big event or maybe for the week for your family or something. "I have just finished buying the meal." would mean a single meal, probably only for one person, that would feed them ONCE. The Swedish word for "meal" is "måltid" and would probably (a lot of the time, at least) suggest that there was a bit of conversation and (hopefully) fun happening at the same time. For example "Vi hade en måltid tillsammans." - "We had a meal together." You didn't just share food for the sake of not going hungry, you had food and a conversation together.
I just got marked wrong for "it is the cat's food" which i get, but the "correction" has no apostrophe which is surely just as wrong as what i selected.
The thing is, i could select from It Is The Cat 's Food Bread Bird Strawberry
So there is LITERALLY NO WAY that i could select "cats' food" from the provided words.
If you're certain that your answer is correct, please consider leaving an error report or attaching a screenshot, so that we have something to send to the developers.
That said, there are bugs with all sentences that feature plural apostrophes, which could also be the cause of your issue. Since I don't know what you answered, it's hard to tell for sure what went wrong.