Rewrite the Expression $3 x ^ { - 4 }$ Using Only Positive Exponents

Rewrite the expression $3 x ^ { - 4 }$ using only positive exponents. Assume that x is not zero.

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