Evaluate the Function at the Indicated Value Of $x = a ^ { 8 }$

Multiple Choice

Evaluate the function at the indicated value of $x = a ^ { 8 }$ $g ( x ) = \log _ { a } x$

A) $- 8$
B) 8
C) 0
D) $\frac { 1 } { 8 }$
E) $- \frac { 1 } { 8 }$