If you actually do what the problem statement tells you to do, the answer falls into your lap.
The attachment shows the triangle reflected across the y-axis (blue), then across the x-axis (red). The red triangle is clearly equivalent to the original being rotated 180° about the origin.
The appropriate choice is ...
... a 180° rotation about the origin
_____
Algebraically, reflection across the y-axis negates the x-coordinate:
... (x, y) ⇒ (-x, y)
and reflection across the x-axis negates the y-coordinate:
... (x, y) ⇒ (x, -y)
Then, reflection across first one axis then the other will result in both coordinates being negated:
... (x, y) ⇒ (-x, -y)
This is precisely what happens when a figure is rotated 180° about the origin.
