For how many pairs (a,b) from (1,2), (3,5), (5,7), (7,11), the polynomial P(x)=x5+ax4+bx3+bx2+ax+1 has exactly one real root?<spanclass=′latex−bold′>(A)</span>4<spanclass=′latex−bold′>(B)</span>3<spanclass=′latex−bold′>(C)</span>2<spanclass=′latex−bold′>(D)</span>1<spanclass=′latex−bold′>(E)</span>0