The correct answer is c. WZ.
In a parallelogram, opposite sides are congruent. Segment ZV is an opposite side to segment WZ. Therefore, segment ZV must be congruent to segment WZ.
If quadrilateral WXYZ is a parallelogram, then the opposite sides of the quadrilateral are congruent and parallel.
In a parallelogram, the corresponding sides of parallel sides are equal in length, and the corresponding angles of parallel angles are equal.
The other answer choices are not correct because they are not opposite sides in the parallelogram.