Rectangle ABCD has length 9 and width 5. Diagonal AC is divided into 5 equal parts at W,X,Y, and Z. Determine the area of the shaded region.
Answer Choices
A. 36
B. \frac{36}{5}
C. 18
D. \displaystyle\frac{4\sqrt{106}}{5}
E. \displaystyle\frac{2\sqrt{106}}{5}