Find $\frac { f ( a + h ) - f ( a ) } { h }$

Find $\frac { f ( a + h ) - f ( a ) } { h }$ for f ( x ) = $-$ x 2 $-$ 6.

A) 6 a
B) $-$ 6
C) h + a
D) $-$ 2 a $-$ h