Answer:
D. (bottom right)
Step-by-step explanation:
A function is a relation where every input has an exact corresponding output.
So, a circle cannot be a function, neither can a vertical line.
If the graph in the top right contained a parabola the opened upwards instead of to the right, it could be a function. But in this case it isn't.
So, by process of elimination, it must be the bottom right graph!
