Simplify the Expression $\left( \frac { r ^ { 5 } r ^ { - 1 } } { r ^ { 6 } r ^ { - 6 } } \right) ^ { 4 }$

Multiple Choice

Simplify the expression. $\left( \frac { r ^ { 5 } r ^ { - 1 } } { r ^ { 6 } r ^ { - 6 } } \right) ^ { 4 }$ Write the answer without using negative exponents. Assume that the variable is restricted to those numbers for which the expression is defined.

A) $r ^ { 4}$
B) $r ^ { 24}$
C) $r ^ { 0}$
D) $r ^ { 16}$