2010 AMC 12A Problem 4

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

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

Full credit goes to MAA for authoring these problems. These problems were taken on the AOPS website.