Which relation is also a function?
{(0, 3), (1, 2), (1, 4), (2, 1)}
{(-1, 3), (0, 2), (3, -1), (3, 2)}
{(2, -4), (2, -2), (2, 1), (2, 3)}
{(-4, -3), (0, -3), (1, -3), (4, -3)}

A function will not have any repeating x values...they all have to be different. They can have repeating y values, just not the x ones.

so ur sets of numbers are all set up like (x,y). Now look through ur answer choices and which one has all different x values ? That will be ur function.

ur answer is : { (-4,-3), (0,-3), (1,-3), (4,-3)}and as u can see, all the x values {-4,0,1,4} are different.