I added a screenshot with the complete question along with the diagram.
Answer:
point Z
Step-by-step explanation:
First, let's consider the plane containing WXY.
Taking a look at the diagram, we can note that this plane is the base of the prism.
Now, the base of the prism is given as a rectangle named WXYZ. All the points of the base lie on the same plane.
Based on the above, point Z would be the fourth point lying on the plane WXY
Hope this helps :)