Let ABCD be a quadrilateral with AB extended to E so that \overline{AB} \equal{} \overline{BE}. Lines AC and CE are drawn to form angle ACE. For this angle to be a right angle it is necessary that quadrilateral ABCD have:
<spanclass=′latex−bold′>(A)</span>all angles equal<spanclass=′latex−bold′>(B)</span>all sides equal<spanclass=′latex−bold′>(C)</span>two pairs of equal sides<spanclass=′latex−bold′>(D)</span>one pair of equal sides<spanclass=′latex−bold′>(E)</span>one pair of equal angles