At the point $x=0$, the function $f(x)=x^{3}$ has
(A) local maximum
(B) local minimum
(C) both local maximum and minimum
(D) neither local maximum nor local minimum
At the point $x=0$, the function $f(x)=x^{3}$ has
(A) local maximum
(B) local minimum
(C) both local maximum and minimum
(D) neither local maximum nor local minimum