Find the Value for the Function $f ( - x )$

Multiple Choice

Find the value for the function.
-Find $f ( - x )$ when $f ( x ) = \frac { x } { x ^ { 2 } + 1 }$

A) $\frac { - x } { x ^ { 2 } + 1 }$
B) $\frac { - x } { x ^ { 2 } - 1 }$
C) $\frac { - x } { - x ^ { 2 } + 1 }$
D) $\frac { x } { - x ^ { 2 } + 1 }$