Answer:
The transformation on the graph is a reflection across the x-axis.
Step-by-step explanation:
A reflection is a transformation representing a flip of a figure. Figures may be reflected in a point, a line, or a plane. When reflecting a figure in a line or in a point, the image is congruent to the preimage. A reflection maps every point of a figure to an image across a fixed line.
In this particular figure, you see that each point is the same number of units away from the x-axis. For instance, with A and A' their both 1 unit away from the x-axis. So this is an automatic indicator that this transformation is a reflection.