Which of the following statements is incorrect?

$\left|x\right|=$ $\{\begin{array}{c}-x;x<0\\ 0;x=0\\ x;x>0\end{array}$ $and\mathrm{sgn}\left(x\right)$ $=\{\begin{array}{c}-1;x<0\\ 0;x=0\\ 1;x>0\end{array}$

$\therefore$  (A) $x\mathrm{sgn}x=\{\begin{array}{c}-x,ifx<0\\ 0,ifx=0\\ x,ifx>0\end{array}\Rightarrow$ $x\mathrm{sgn}x=\left|x\right|$

(B) $\left|x\right|\mathrm{sgn}x=(-x)(-1)=x,$       if                        $x<0$

                   $\left(0\right)\left(0\right)=0,$                      if                        $x=0$

                   $\left(x\right)\left(1\right)=x,$                        if                        $x>0$

$\Rightarrow \left|x\right|\mathrm{sgn}x=x$

(C) $x\left(\mathrm{sgn}x\right)\left(\mathrm{sgn}x\right)=x$

(D) $\left|x\right|{\left(\mathrm{sgn}x\right)}^3=(-x){(-1)}^3=x$   if   $x<0$

                     $\left(0\right){\left(0\right)}^3=0,$                      if                        $x=0$

                     $\left(x\right){\left(1\right)}^3=x,$                        if                        $x>0$

$\therefore \left|x\right|{\left(\mathrm{sgn}x\right)}^3=xnot\left|x\right|$ .