Specify the Domain Of $( g \circ f ) ( x )$

Multiple Choice

Specify the domain of $( g \circ f ) ( x )$ for the pair of functions $f ( x ) = \sqrt { x + 9 } \text { and } g ( x ) = 5 x + 9$

A) $( - \infty , 9 ]$
B) $[ 0 , \infty )$
C) $( - \infty , \infty )$
D) $[ - 9 , \infty )$