The vertex of the parabola in the day-plane above is (0,c). which of the following is the tru about the parabola witg the equation y=-a(x-b)^2+c? a.) the vertex is (b, c) and the graph opens upward. b.) the vertex is (b, c) and the graph opens downward. c.) the vertex is (-b, c) and the graph opens upward. d.) the vertex is (-b, c) and the graph opens downward.