Find the Function Value $\mathrm { f } ( \mathrm { x } ) = \left( \frac { 1 } { 4 } \right) ^ { \mathrm { x } }$

Multiple Choice

Find the function value. If the result is irrational, round your answer to the nearest thousandth.
-Let $\mathrm { f } ( \mathrm { x } ) = \left( \frac { 1 } { 4 } \right) ^ { \mathrm { x } }$ . Find $\mathrm { f } ( 3 )$ .

A) $\frac { 1 } { 12 }$
B) 64
C) $\frac { 1 } { 64 }$
D) $\frac { 1 } { 81 }$