The transformed figure has the opposite orientation (A'B'C'D' is counterclockwise, whereas ABCD is clockwise), so a reflection is involved. The sgment C'D' is still at the bottom, as is CD, so the reflection must be across a vertical line.
In the attached, the light-blue figure A''B''C''D'' shows the reflection of ABCD across the y-axis. It is easy to see that figure A'B'C'D' is a translation of that 5 units downward.
The appropriate choice is the 2nd one ...
... Reflection over the y-axis followed by a translation down by 5 units.
