Determine the Function Value $f ( x ) = \log _ { a } x$

Multiple Choice

Determine the function value.
-Suppose $f ( x ) = \log _ { a } x$ and $f ( 4 ) = 2$ . Find $f \left( \frac { 1 } { 16 } \right)$

A) $- 4$
B) $\frac { 1 } { 2 }$
C) $- 2$
D) 4