Answer:
D
Step-by-step explanation:
To see if a set order of points is a function, you have to do the vertical line test. If there are two points on the same x-axis, like (2,3) and (2,6), then it isn't a function. Although, if there are two points on the same y-axis, like (2,5) and (4,5), then yes, it is a function.
-hope it helps
