If the discriminant of ax^2\plus{}2bx\plus{}c\equal{}0 is zero, then another true statement about a, b, and c is that:
<spanclass=′latex−bold′>(A)</span>they form an arithmetic progression<spanclass=′latex−bold′>(B)</span>they form a geometric progression<spanclass=′latex−bold′>(C)</span>they are unequal<spanclass=′latex−bold′>(D)</span>they are all negative numbers<spanclass=′latex−bold′>(E)</span>only b is negative and a and c are positive