non-negative
1) Considering that this expression yields the following:
![\begin{gathered} (\sqrt[]{b})^2= \\ \sqrt[]{b^2}=b \\ \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/9435d1mkq4dgi0uanyds6i65hykmtigqvm.png)
2) Then we can state that the b must be a non-negative value since the square root does not admit a negative number, otherwise, it would cause an undefinition.
3) Hence, the answer is D)b must be a non negative value