Perform the Indicated Operation $\left( 9 x ^ { - 12 } \right) ^ { - \frac { 1 } { 2 } }$

Multiple Choice

Perform the indicated operation. Assume all variables represent positive numbers. $\left( 9 x ^ { - 12 } \right) ^ { - \frac { 1 } { 2 } }$

A) $- 3 x ^ { 6 }$
B) $\frac { x ^ { 6 } } { 3 }$
C) $9 x ^ { 6 }$
D) $\frac { 1 } { 3 x ^ { 6 } }$