The quadratic equation x2+6x+9=0 has a discriminant equal to zero. What does this imply about the graph of y=x2+6x+9?
a) It does not intersect the x-axis because its graph is always above it.
b) It cuts the x-axis at two distinct points.
c) It touches the x-axis at exactly one point.
d) It lies completely below the x-axis because the parabola opens downward.