When a Quadratic Equation Is Solved Graphically, Which Feature of the Graph

When a quadratic equation is solved graphically, which feature of the graph represents the solution(s) to the equation?

A) The mean gradient of the curve
B) The point(s) at which the graph crosses the vertical (y) axis
C) The point(s) at which the graph crosses the horizontal (x) axis
D) The area between the curve and the horizontal axis