According to Wikipedia: "<span>In mathematics, a function
is a relation between a set of inputs and a set of permissible outputs
with the property that each input is related to exactly one output."
So based of this we need to look for a set where one of the x values or the y values is the same, and the other number is different.
Answer: B. (1,4) and (1,1) both have the same x, but different y! </span>
