Teddy is writing a proof about the figure shown on the coordinate plane below. He wants to show that quadrilateral WXYZ is a parallelogram. Which statement proves that WXYZ is a parallelogram?

A. Show that segments WX and YZ have equal slopes.

B. Show that segments WX and YZ have equal lengths.

C. Show that the midpoints of segments WY and XZ are the same point.

D. Show that segments WX and XY have slopes that are opposite reciprocals of each other.