Find the Domain of the Composite Function F $f ^ { \circ } g$

Multiple Choice

Find the domain of the composite function f $f ^ { \circ } g$
- $$\mathrm { f } ( \mathrm { x } ) = 7 \mathrm { x } + 14 ; \quad \mathrm { g } ( \mathrm { x } ) = \mathrm { x } + 7$$

A) $\{ x \mid x$ is any real number $\}$
B) $\{ x \mid x \neq 9 \}$
C) $\{ x \mid x \neq - 7 , x \neq - 2 \}$
D) $\{ x \mid x \neq - 9 \}$