Write the Expression with Only Positive Exponents and Evaluate If $3 x ^{- 3}$

Multiple Choice

Write the expression with only positive exponents and evaluate if possible. Assume all variables represent nonzero real
numbers.
- $3 x ^{- 3}$

A) $- 9 x$
B) $- \frac { 1 } { 9 x }$
C) $\frac { 1 } { 27 x ^ { 3 } }$
D) $\frac { 3 } { x ^ { 3 } }$