Answer: Only reflection across y=-x
Step-by-step explanation:
Line y=-x, slope -1 is perpendicular bisector of base running from (-8,1) to (-1,8), slope 1, and figure is isosceles trapezoid so even though the figure is cut off we know line is also perpendicular bisector of the other base.
Although (-8,1) rotates to (-1,8) about (-1,-1) through 90°, the other vertices don't. Always check more than one vertex.
If you draw some segments perpendicular to y=-7x+1, you see that the points on left do not map to points on right.