Simplify the Exponential Expression $\frac { r ^ { - 6 } } { r ^ { - 4 } }$

Multiple Choice

Simplify the exponential expression. Write the result using only positive exponents.
- $\frac { r ^ { - 6 } } { r ^ { - 4 } }$

A) $\frac { 1 } { \mathrm { r } ^{10 }}$
B) $\frac { 1 } { \mathrm { r } ^ { 2 } }$
C) $\mathrm { r }^{ 10}$
D) $r ^ { 2 }$