For how many positive real numbers a has the equation a2x2+ax+1−7a2=0 two distinct integer roots?<spanclass=′latex−bold′>(A)</span>1<spanclass=′latex−bold′>(B)</span>2<spanclass=′latex−bold′>(C)</span>3<spanclass=′latex−bold′>(D)</span>Infinitely many<spanclass=′latex−bold′>(E)</span>None of above