The correct answer for the completion exercise shown above is: "Rectangle".
Then, the complete sentece is: The only way to circumscribe a circle around a parallelogram is to make the parallelogram a rectangle.
The explanation is shown below:
By definition, a parallelogram is a four sided polygon (or a quadrilateral). Therefore, to circumsbribe a circle around this figure, all the vertexes must lie on the circle and it must have four angles of 90 degrees. So, it must be a rectangle.
