Question

which graph shows a function?

Explanation:

A graph represents a function if it passes the Vertical Line Test: any vertical line drawn on the graph intersects it at most once.

1. Top-left graph: A vertical line would intersect the graph twice, so it is not a function.
2. Top-right graph: Every vertical line intersects the graph at most once, so it is a function.
3. Bottom-left graph: A vertical line would intersect the graph twice (at the open/closed points), so it is not a function.
4. Bottom-right graph: A vertical line would intersect the graph infinitely many times, so it is not a function.

Answer:

The top-right parabola graph (opening upwards with vertex below the x-axis) shows a function.