The correct answer is a reflection in the y-axis, followed by a rotation 90° clockwise about the origin. Option B is the right choice.
To see this, let's imagine that we can superimpose parallelogram ABCD onto parallelogram A'B'C'D'.
In order to do this, we need to perform a transformation that will move ABCD to the same position as A'B'C'D'.
If we reflect ABCD in the y-axis, we will get parallelogram A'B'C'D'. However, A'B'C'D' is rotated 90° clockwise relative to ABCD. To fix this, we can rotate ABCD 90° clockwise about the origin.
The following image shows the two parallelograms superimposed after the reflection in the y-axis and the rotation 90° clockwise about the origin:
Therefore, the series of transformations that shows that parallelogram ABCD is congruent to parallelogram A'B'C'D' by superimposing one onto the other is a reflection in the y-axis, followed by a rotation 90° clockwise about the origin.
Option B is the right choice.