Find the Critical Number(s), If Any of the Function $f(t)=2 t^{\frac{3}{4}}-4 t^{\frac{1}{4}}$

Multiple Choice

Find the critical number(s) , if any of the function $f(t) =2 t^{\frac{3}{4}}-4 t^{\frac{1}{4}}$

A) $\frac{4}{9}$
B) 0, $\frac{4}{9}$
C) $\frac{2}{3}$
D) 0, $\frac{2}{3}$