Hello!
Since this is a reflection, then the new figure has to be congruent since we're not changing the size or the shape.
Now, (x, y) is located in the First Quadrant, whereas (x, -y) is located in the Fourth Quadrant. If we're going from the First Quadrant to the Fourth Quadrant, then this has to be a reflection across the x-axis.
The correct answer is "Yes, ΔP'Q'R is a reflection of ΔPQR over the x-axis." :)