Start with the basic salt, I think you may find it easier. Then look at X, Y, and Z. If the salt is basic, which will react with it? For example, if X was HCl, and the base was NaOH, how would they react? One of the choices of X, Y, or Z will behave as a weak acid.
Then go back and find the other pair and how might it react with X, Y, or Z (it will be a different reaction).