Simplify the Expression $r ^ { - 3 }$ A) $r ^ { 1 / 3 }$

Multiple Choice

Simplify the expression. Write the result using positive exponents only.
- $r ^ { - 3 }$

A) $r ^ { 1 / 3 }$
B) $\frac { 1 } { \mathrm { r } ^ { 3 } }$
C) $- \frac { 1 } { r ^ { 3 } }$
D) $- r ^ { 3 }$