AHSME 1993 Problem 9

Country $A$ has $c\%$ of the world's population and $d\%$ of the worlds wealth. Country $B$ has $e\%$ of the world's population and $f\%$ of its wealth. Assume that the citizens of $A$ share the wealth of $A$ equally,and assume that those of $B$ share the wealth of $B$ equally. Find the ratio of the wealth of a citizen of $A$ to the wealth of a citizen of $B$. $\text{(A) } \frac{cd}{ef} \text{(B) } \frac{ce}{ef} \text{(C) } \frac{cf}{de} \text{(D) } \frac{de}{cf} \text{(E) } \frac{df}{ce}$