$\sqrt[3]{x^{4}}$ can be written as $x^{}\frac{4}{3}$, which is equivalent to II and III. 
If $x\textgreater0$, which of the following is equivalent to $\sqrt[3]{x^{4}}$ ?  $ $ $I. x+x^{\frac{1}{3}}$  $ $ $II. \left(x^{\frac{1}{3}}\right)^{4}$  $ $ $III. x^{2}\left(x^{-\frac{2}{3}}\right)$ 

1. None 
2. $I$ and $II$ only 
3. $II$ and $III$ only 
4. $I$, $II$, and $III$ 