For a relation to be a function, each input have to give a single output, that is, each x value must be related to only one y value.
In the given realtion, we already have associations for the x values 2, -9, 14 and 5, so if we add another relation for one of thouse x values, the relation won't be a function anymore.
From the alternatives, we can see that the only one that has a relation of one of the "x" listed above is the alternative with 2:
So, the answer is the fourth alternative.