A rectangular piece of paper, PQRS, has PQ=20 and QR=15. The piece of paper is glued flat on the surface of a large cube so that Q and S are at vertices of the cube. (Note that \triangle{QPS} and \triangle{QRS} lie flat on the front and top faces of the cube, respectively.) The shortest distance from P to R, as measured through the cube, is closest to
Answer Choices
A. 17.0
B. 25.0
C. 31.0
D. 17.7
E. 18.4