Evaluate the Function at the Indicated Value Of $x = a ^ { 2 }$

Multiple Choice

Evaluate the function at the indicated value of $x = a ^ { 2 }$
$g ( x ) = \log _ { a } x$

A) $- 2$
B) $\frac { 1 } { 2 }$
C) $- \frac { 1 } { 2 }$
D) 2
E) 0