Yes. The context, of course is most probably - A mother who got a remark from her child "I do not understand", hence "who is supposed to understand this" comes after.
DL often strictly differs between "(tam)to" = the/that and "toto" = this. Why this exception.
Yes, of course. But why is czech "to" translated to english "this" (only and just) in this exercise? And not to english "that"?
both this and that are accepted here
Sometimes we relax the strict distinguishing when the sentence calls for that.
I am not convinced by this explanation. I choose "this" because it was the only possibility in the app. Would "that" also be acceptable? The sentence is not in a context, so ... how does the sentence call for whatever?
And yes, Randonneur3, this is really subtle. I saw it only after I made my remark ;-)
This is a programme. It gives you the the correct possible words randomly. But they are always there. If you will repeat this exercise more times, it is very likely that you will get this question with the word "that" as a solution to form the correct answer/sentence.
how does the sentence call for whatever?
Well, it is really mostly the feel for our native language. You can't use "toto" here in a good way (although you coul use tohle).
I believe that when “to” is used as a demonstrative pronoun it can be THIS or THAT. But when “to” is used as a demonstrative adjective, then it can only be THAT. Who is this/that? = Kdo je to? This child is tall.= Toto dítě je vysoké. That child is tall.=To dítě je vysoké. Someone please correct me if I’m wrong.