The answer is F. A set of ordered pairs that describes a function cannot have any y-value repeated.
~~
Why??
F - it can be a function even if a y - value repeats itself its the x - values that cannot repeat in order to be a function.
G - this is true as stated above.
H - a mapping is a function if each x - value is paired with only one y - value. If an x - value was paired with multiple y - values then its the same thing as repeated x - values.
J - this is true. To check if a graph is a function try the vertical line test. Simply take a ruler holding it vertically ( up and down ) and place it over a point on the graph. If there is another point lined up with the first one ( above or below ), then it is NOT a function.
~~
I hope that helps you out!!
Any more questions, please feel free to ask me and I will gladly help you out!!
~Zoey