Respuesta :

[tex](16 a^{3} b^{4} )^ \frac{3}{4} [/tex]

Expand,

[tex] 16^{ \frac{3}{4} } a^{3* \frac{3}{4} } b^{4* \frac{3}{4 } } [/tex]
= [tex]8 a^{ \frac{9}{4} } b^{3} [/tex]

So the third choice would be your answer!

Hope this helps!