To maintain congruency, there must be no change of size, so any coefficient of x or y is ruled out.
That leaves (x+1, y-4), (x-2, y), (x+2, y), (-x, y), (x-4, y+2). 4 of these involve shifts right/left and/or up/down which will result in overlaying. The one remaining option is (-x, y) which is a simple reflection about the y-axis. This one preserves congruency.