The expression a+yy−a−yaa+ya+a−yy, a real, a=0, has the value −1 for:<spanclass=′latex−bold′>(A)</span>all but two real values of y<spanclass=′latex−bold′>(B)</span>only two real values of y<spanclass=′latex−bold′>(C)</span>all real values of y<spanclass=′latex−bold′>(D)</span>only one real value of y<spanclass=′latex−bold′>(E)</span>no real values of y