AMC 12 2010a Problem 4

If $x<0$, then which of the following must be positive?

\textbf{(A)}\ \frac{x}{\left|x\right|} \textbf{(B)}\ -x^2 \textbf{(C)}\ -2^x \textbf{(D)}\ -x^{-1} \textbf{(E)}\ \sqrt[3]{x}