Let W, X, Y and Z be four different digits selected from the set
\{1,2,3,4,5,6,7,8,9\}
If the sum \dfrac{W}{X}+\dfrac{Y}{Z} is to be as small as possible, then \dfrac{W}{X}+\dfrac{Y}{Z} must equal
Answer Choices
A. \dfrac{2}{17}
B. \dfrac{3}{17}
C. \dfrac{17}{72}
D. \dfrac{25}{72}
E. \dfrac{13}{36}