AMC 8 1994 Problem 20

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 $\text{(A)}\ \dfrac{2}{17} \text{(B)}\ \dfrac{3}{17} \text{(C)}\ \dfrac{17}{72} \text{(D)}\ \dfrac{25}{72} \text{(E)}\ \dfrac{13}{36}$