Let f(x)\equal{}\sqrt{ax^2\plus{}bx}. For how many real values of a is there at least one positive value of b for which the domain of f and the range of f are the same set?
<spanclass=′latex−bold′>(A)</span>0<spanclass=′latex−bold′>(B)</span>1<spanclass=′latex−bold′>(C)</span>2<spanclass=′latex−bold′>(D)</span>3<spanclass=′latex−bold′>(E)</span>infinitely many