1963 AHSME Problem 12

Three vertices of parallelogram PQRS are P(-3,-2), Q(1,-5), R(9,1) with P and R diagonally opposite. The sum of the coordinates of vertex S is:

\textbf{(A)}\ 13 \qquad \textbf{(B)}\ 12 \qquad \textbf{(C)}\ 11 \qquad \textbf{(D)}\ 10 \qquad \textbf{(E)}\ 9

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