Which set of ordered pairs represents y as a function of x? O {(3, 3), (3, 4), (4,3), (4,4)}
O {(2,-1), (4,-2), (6,-3), (8,4)}
O {(0,0), (1, 1), (1,0), (2, 1)}
O {(1,-5),(1,5), (2, -10), (2, -15)}

I believe the answer is the second one {starts with (2,-1)}.
To be considered a function, the input which is the x value can only have one output which is the y value. The others have at least one input with multiple outputs.

There is no association.