Evaluate If Possible $\left( \frac { 16 } { 81 } \right) ^ { 1 / 4 }$

Multiple Choice

Evaluate if possible. If the expression is not a real number, so state.
- $\left( \frac { 16 } { 81 } \right) ^ { 1 / 4 }$

A) 24
B) $\frac { 2 } { 3 }$
C) $\frac { 3 } { 2 }$
D) 6