Answer: H
Explanation:
The rule for a graph to be a function is if there are not 2 points that have the same x.
You can do a vertical line test. If you held up a vertical line(line that goes straight up and down) to both of these curves, across the entire curves(everywhere). The curves do not hit that vertical line 2 or more times.
Since both curves pass the vertical line test. They are both functions.