Let side AD of convex quadrilateral ABCD be extended through D, and let side BC be extended through C, to meet in point E. Let S represent the degree-sum of angles CDE and DCE, and let S′ represent the degree-sum of angles BAD and ABC. If r=S/S′, then:<spanclass=′latex−bold′>(A)</span>r=1 sometimes, r>1 sometimes<spanclass=′latex−bold′>(B)</span>r=1 sometimes, r<1 sometimes<spanclass=′latex−bold′>(C)</span>0<r<1<spanclass=′latex−bold′>(D)</span>r>1<spanclass=′latex−bold′>(E)</span>r=1