In the diagram, ABCD is a square with side length 6, and WXYZ is a rectangle with ZY=10 and XY=6. Also, AD and WX are perpendicular. If the shaded area is equal to half of the area of WXYZ, the length of AP is
Answer Choices
A. 1
B. 1.5
C. 4
D. 2
E. 2.5