## Geometry: Common Core (15th Edition)

It is true that the diagonals of a parallelogram bisect each other, but in this exercise, we are only given that one diagonal, $\overline{AC}$, bisects the other one, $\overline{BD}$. Nothing is said about $\overline{BD}$ bisecting $\overline{AC}$. Therefore, we cannot determine that $ABCD$ is a parallelogram based on the information we are given.