Derp, I was so upset that it wasn't accepting the right answer and I realized they're looking for the Polish.
So I just found something strange... if you, like me, can't think in Slavic without thinking Cyrillic, you can type these lessons with Russian alphabet. Out of frustration I just typed Ем обяд and I got it right.
It's not a problem of Polish, but of English. Simplifying, our śniadanie/obiad/kolacja are breakfast/lunch/dinner in the US, and breakfast/dinner/supper in Great Britain. It seems that even in Great Britain it isn't that popular. But we in Poland are usually taught the 'more British' version, that's why for you (and me as well) 'obiad' is rather 'dinner'. But Duolingo is an American company, so we usually go with the American translation as the default.
In the previous question there was no option for the right answer. How can I report a mistake?
Obiad... lunch? Neah... that's wrong on so many levels. Lunch is 11:30... Obiad 16:00...