Which sequence of transformations takes A to its image A'?
A. a translation 1 unit down followed by a reflection in the x-axis
B. a reflection in the x-axis, followed by a translation 1 unit down
C. a translation 3 units to the left, followed by a clockwise rotation 180 about the origin
D. a reflection in the y-axis, followed by a clockwise rotation 180 about the origin