Answer:
The second and fourth options
Explanation:
A function is where one the inputs have only one output. In this case all we have to do is look at the x value (x,y) and see when it goes 1,2,3,4 and that means there are no repeating x and in that case each input has only one output. If you look at the other ones they have a repeating x and that means the input has two outputs and therefore it isn't a function.