Rewrite as a Radical Expression and Simplify If Possible $\left(b^{7}\right)^{2 / 7}$

Multiple Choice

Rewrite as a radical expression and simplify if possible. Assume all variables represent nonnegative real numbers.
- $\left(b^{7}\right) ^{2 / 7}$

A) $b^{2 / 49}$
B) $b^{9 / 7}$
C) $b^{1 / 7}$
D) $b^{2}$