For which pair (A,B),
x2+xy+y=Ay−xy=B
has no real roots?<spanclass=′latex−bold′>(A)</span>(1/2,2)<spanclass=′latex−bold′>(B)</span>(−1,1)<spanclass=′latex−bold′>(C)</span>(2,2)<spanclass=′latex−bold′>(D)</span>(1,1/2)<spanclass=′latex−bold′>(E)</span>(2,2/3)