# Which one of the following is a concerto that must be selected?

AnnaC on January 4, 2020

Can you please provide an explanation for the logic that goes behind this question?

How can you infer that Y must be selected?

Replies

Skylar on January 5, 2020

@AnnaC, happy to help.

We are asked to identify one concerto that must always be selected.

To answer this, we should first look to the most restricted areas of the game. Rule #3 provides significant restrictions, because it states: X -> NOT Z and NOT P. This is of special interest to us because X and Z are both Vivaldi's concertos, but they cannot be selected together. Remember, Vivaldi only has three concertos and exactly two must be selected, so this means that one of the selected concertos will be either X or Z and the other will always be Y.

Therefore, Y must always be selected.

Does that make sense? Please let us know if you have any other questions and best of luck with your studies!

AnnaC on January 5, 2020

Hi Skylar, yes that makes sense! Thank you for your help.