Answer:
The graph in (A)
Explanation:
Negative discriminant of a quadratic function implies the corresponding quadratic equation ax^2+bx+c=0 does not have any real solutions (it still has solutions in the complex domain, however). Graphically, this corresponds to a parabola that never intersects the x axis for any value x, i.e. it lies either fully above or fully below the x axis. This situation is depicted in the case (A), where the parabola lies below the x axis and has no x-intercepts.
The cases (B), (C), and (D) all intersect the x axis in at least one point.