"Do you not see the buses?"
Translation:Nem látjátok a buszokat?
I find this a particularly "tricky" question. it is a multiple choice. One choice is using the singular you and another one the plural you (the one given here as the only acceptable answer). At first sight both appear correct. The tricky part is that there is "az" instead of "a" in front of buszokat, and this is the reason why the singular version is not accepted. I know that one should be careful and make sure that each word is correct but I can imagine someone with a big smile saying: "I got you".
That has always been my understanding - the system picks things at random as distractor sentences, some of which are obvious nonsense and some of which are only very subtle nonsense. (And some of which even happen to be correct, but the system does not know it because that combination had not been added as an alternative.)