2011 Cayley Problem 15

The points Q(1,-1), R(-1,0) and S(0,1) are three vertices of a parallelogram. The coordinates of the fourth vertex of the parallelogram could be

\textbf{(A)}\ (-2,2)\quad \textbf{(B)}\ (0,-1)\quad \textbf{(C)}\ (0,0)\quad \textbf{(D)}\ (\frac{3}{2},\frac{1}{2})\quad \textbf{(E)}\ (-1,1)

If there are no answer choices shown, enter a numerical answer.

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