AMC 10 2000 Problem 15

Two non-zero real numbers, a and b, satisfy a b=a-b. Find a possible value of \dfrac{a}{b}+\dfrac{b}{a}-a b.

Answer Choices
A. -2
B. -\dfrac{1}{2}
C. \dfrac{1}{3}
D. \dfrac{1}{2}
E. 2