Answer:
see attached
Explanation:
Reflection in the line y=x reverses the coordinates of each point:
(x, y) ⇒ (y, x)
So, for example, the upper left corner of figure A, which is (1, -2), gets reflected to the point (-2, 1). The inside corner (3, -3) gets reflected to (-3, 3).
The whole reflected figure is drawn in the attachment.
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Additional comment
If you have trouble visualizing the result, you can draw the figure, axes, and line of reflection on a transparent overlay. Then turn it upside down and line up the axes and line of reflection. This will show the figure in its reflected position.
Here, the axis intersect on the line of reflection. If you have a reflection line somewhere else on the grid, you need to mark a point on the line of reflection. It will be "invariant," in the same place on the right side up and upside down orientations of your overlay.