TELL HOW TO DO IT AND PLS DONT STEAL POINTS

The last one is a function.

Step-by-step explanation:

When the x value corresponds to different y values e.g. (1,2)(1,1), then it automatically isn't a function.  Another simple way to find out if something is a function is to graph and try the vertical line test.  If the line passes through multiple points on it's way down, then it's not a function.

Hope that helps :)