Final answer:
The equation y=-x²+6x-8 describes a vertical parabola because it is in quadratic form with a leading coefficient indicating a downward opening.
Step-by-step explanation:
The statement that describes the equation y=-x²+6x-8 is that it represents a vertical parabola. This is because the equation is in the form of y=ax²+bx+c, where a, b, and c are constants, and the coefficient 'a' is negative, indicating the parabola opens downwards. The graph of a linear equation like y=a+bx is a straight line. Thus, answers related to hyperbolas and horizontal lines do not apply.