Answer:
D is the correct answer.
Step-by-step explanation:
When given points, one way to tell if it is a function is to see if the x-coordinate changes. If all the x-coordinates are different, then it is a function. If there is a group of x-coordinates that are the same, then you need to check the y-coordinate. If the y-coordinate is the same with the same x-coordinate, then it is still a function [Example: (12, 15), (12, 15) is a function, but (12, 15), (12, 18) is not)
