Well, the y axis is the one that goes up and down, so it's pretty clear that it's flipped over that. After it gets reflected over the y axis, the -2 changes into 2 (so -2 is multiplied by -1) as it is the x coordinate, making the center (2,5). After that, you'd want to get the y value down by 4 to match it up with (2,1), meaning that the second option down is right!
