Find the Function Value $f ( x ) = \left( \frac { 1 } { 5 } \right) ^ { x }$

Multiple Choice

Find the function value. If the result is irrational, round your answer to the nearest thousandth.
-Let $f ( x ) = \left( \frac { 1 } { 5 } \right) ^ { x }$ . Find $f ( - 1 )$

A) $- \frac { 1 } { 5 }$
B) $- 5$
C) $\frac { 1 } { 5 }$
D) 5