Write the Expression with Only Positive Exponents and Evaluate If $3 x ^ { - 4 }$

Multiple Choice

Write the expression with only positive exponents and evaluate if possible. Assume all variables represent nonzero real
numbers.
- $3 x ^ { - 4 }$

A) $\frac { 1 } { 81 x ^ { 4 } }$
B) $\frac { 3 } { x ^ { 4 } }$
C) $- \frac { 1 } { 12 x }$
D) $- 12 x$