AMC 12 2001 Problem 9

Let $f$ be a function satisfying $f(xy) = \frac{f(x)}y$ for all positive real numbers $x$ and $y$. If $f(500) =3$, what is the value of $f(600)$?

$\text{(A)}\ 1 \text{(B)}\ 2 \text{(C)}\ \frac52 \text{(D)}\ 3 \text{(E)}\ \frac{18}5$