Express Using Positive Exponents $\frac { 1 } { x ^ { - m } }$

Multiple Choice

Express using positive exponents. Then simplify.
- $\frac { 1 } { x ^ { - m } }$

A) $x ^ { m }$
B) $m x$
C) $\frac { 1 } { \mathrm { xm } }$
D) $x ^ { - m }$