If $\frac{a}{b}<-\frac{c}{d}$ where $a$, $b$, $c$, and $d$ are real numbers and $bd \not= 0$, then:
$\text{(A)}\ a \; \text{must be negative} \qquad \text{(B)}\ a \; \text{must be positive} \qquad$
$\text{(C)}\ a \; \text{must not be zero} \qquad \text{(D)}\ a \; \text{can be negative or zero, but not positive } \\ \text{(E)}\ a \; \text{can be positive, negative, or zero}$
Notice that $b$ and $d$ are irrelevant to the problem.  Also notice that the negative sign is irrelevant since $c$ can be any real number.  So the question is equivalent to asking what values $a$ can take on given the inequality $a<c$.  The answer, is of course, that $a$ could be anything, or $\boxed{\textbf{(E) } \ a \; \text{can be positive, negative, or zero}}$
~ proloto