1. Determine the graph behavior at the zero(s) of the polynomial function f(x)=x^2 - 6x + 9.
A. The graph of the function touches the x-axis at x = -3 and x = 3.
B. The graph of the function crosses the x-axis at x = -3 and x = 3.
C. The graph of the function touches the x-axis at x = 3.
D. The graph of the function crosses the x-axis at x = -3.