My possibilities are:

a X->->Y, X->->Z

b Y->->X, Y->->Z

c Z->->X, Z->->Y

This is an example of an exam question which I will most definitely get. The problem is I don't understand the first thing about this 4th database normalisation technique.

What I got from many Google-searches and YouTube-movies is that if X->->Y that means that for 1 X-value there are multiple Y values.

But how do I determine which one of these rules applies to the given table?

I've included a screenshot of set table as an attachment, if anyone could help me figure out this 4NF I would be ever grateful.