I'm pretty sure that it would be the middle one as, if we read the graph as the top-left coordinate plane as 1, the top, right coordinate plane as 2, the bottom-left coordinate plane as 3, and the bottom-right coordinate plane as 4...
Your initial ABC triangle (being in the coordinate plane of 1) would flip over the y-axis, placing it into the coordinate plane of 2. By turning 180 degrees, it sends it to coordinate plane 3.
hope this helps :)