Write the Word or Phrase That Best Completes Each Statement $$\left( \frac { 81 s ^ { 12 } r ^ { - 4 } } { 16 s ^ { - 4 } r ^ { 4 } } \right) ^ { 3 / 4 }$$

Multiple Choice

Write the word or phrase that best completes each statement or answers the question.
Write the expression by using rational exponents rather than radical notation.
- $$\left( \frac { 81 s ^ { 12 } r ^ { - 4 } } { 16 s ^ { - 4 } r ^ { 4 } } \right) ^ { 3 / 4 }$$

A) $\frac { 27 s ^ { 6 } } { 8 }$
B) $\frac { 27 s ^ { 12 } } { 8 r ^ { 6 } }$
C) $\frac { 3 s ^ { 16 } r ^ { 8 } } { 2 }$
D) $\frac { 3 s ^ { 12 } } { 2 r ^ { 6 } }$