9. Let the function $f(x)=x(x-1)^{2}(x-2)^{3}(x-3)^{4}$. Then the point of local maximum of the function $y=f(x)$ is ( ).
(A) $x=0$
(B) $x=1$
(C) $x=2$
(D) $x=3$
9. B.

From the graph, we know that $x=1$ is a point of maximum value for the function, $x=3$ is a point of minimum value, and $x=0,2$ are not points of extremum.