To determine whether the given graph represents a function, we can use the vertical line test. This test checks if any vertical line intersects the graph at more than one point. If a vertical line crosses the graph at only one point for every possible $x$-value, then the graph represents a function.

From the uploaded image:

1. The graph appears to cross multiple vertical lines only once along the $x$-axis. For example, if we were to draw vertical lines at any point along the graph, they would intersect the curve only at one point.
2. Therefore, this graph passes the vertical line test, confirming that it is a function.

Thus, the answer is: F (Function).

Would you like more details or have any questions about this? Here are five follow-up questions that might deepen your understanding:

1. What is the vertical line test, and why does it determine if a graph is a function?
2. Can a function have more than one $y$-value for a given $x$-value?
3. How would this graph look if it were not a function?
4. Could you describe the possible domain and range of the function shown?
5. How does this function behave as $x \to \infty$ or $x \to -\infty$?

Tip: When checking if a graph is a function, always try to visualize or sketch vertical lines. If any line crosses the graph more than once, the graph fails the function test.