What set of reflections would carry triangle abc onto itslelf?

y axis, x axis, y axis, x axis

Explanation:

Reflecting an object over the y axis twice will have it end up in its starting position. The same can be said for the x axis as well. It doesn't matter that the x axis reflections aren't grouped next to each other, nor the y. So in a sense, two x axis reflections undo each other, so do the y axis reflections, and we end up with the same image as shown in the diagram.