Answer
-2
Work Step by Step
$-16^{\frac{1}{4}}=-(\sqrt[4] 16)=-(2)=-2$
Since the negative sign is not in parentheses with the 16, we only apply the exponent to the 16. In this case, we are taking the opposite of $\sqrt[4] 16$.
We know that $\sqrt[4] 16=2$, because $2^{4}=16$