None of the given answers are correct. We can check that fairly quickly:
[tex]4\sqrt[3]{4}=\sqrt[3]{4^4}=\sqrt[3]{4}=\sqrt[3]{256}[/tex]
Now let's do the same thing for given answers:
[tex]a) 2\sqrt[3]{16}=\sqrt[3]{8\cdot 16}=\sqrt[3]{128}\\
b) 2\sqrt[3]{64}=\sqrt[3]{8\cdot 64}=\sqrt[3]{512}\\
[/tex]
I don't have to continute, it's pretty obvious that answers C and D are wrong (notice we multiply by 4 and on top of that we square the third root).
